Need help understanding

I apologize as this is might be long. My bf is a recovering heroin addict and I know next to nothing about heroin. He is 5 months sober and I think he is doing great. He moved far away from his old life and keeps busy working and leading a healthy life style.
However 2 months ago he had to go back to his old town for court and to see his son (currently in foster care and hes trying hard to get him back. ) While there, his dad stayed with him in a hotel and kept him busy renovating his old house to be put up for sale. Then he decided to stay an extra day and for most of that day he was unavailable and nobody could get ahold of him. He told me he was out of cell service. Later I found out that he had his son for a few hours that afternoon and they went to visit his sons mom (his ex and also a heroin addict) later that night, she contacted me through her sons social media and said a lot of mean things, which caused her son to be incredibly upset. I talked with his foster mom and we got him calmed down. The next morning my bf left his dads to make the 9 hour trip home. 4 hours into the trip I texted him and he said he was in a city that is still 8 hours away. So for 3 hours I have no clue what he was doing and he said he was shopping for some car stuff. Somehow his 9 hour trip took 12 and when he got home he was grumpy and irritable in a way I haven't seen before. The next morning he slept in til almost noon and when I went to wake him around 10 he was incredibly groggy and said he would be up soon. His ex started messaging ne again about how she knew he was high when she saw him. Now this person really cant let him go and hates that he got clean and moved on and is getting custody of their son. She also lies like crazy so I dont know what to think. She then showed me a screen shot from some guy where he said he did come over and they "did a few dragons and he bought some syde" I dont k ow what that means. He said he bought an amp off him and they burnt some cds and that was that. I know he did but an amp off someone when he was there. I showed it to him and he said it must be a fake profile she created because he didnt do that. He was very upset that I was questioning his sobriety. More upset though that I thought he might be lying since he hasn't lied to me before. He went and worked on his car the rest of the day. When he came in we watched a movie and he started to fall asleep. I was like how can u be so tired when u slept so long. He kept falling asleep and waking up. He was also super twitchy in bed that night. All of it just made me so paranoid and I dont know what to believe. He seemed off for a couple weeks to be honest. We had a long distance relationship and he was living with my sister and his brother (ya I know that's kinda funny that we are dating each others siblings) I was not there to witness any more odd behavior but he was distant in texting me and was short with me. My sister said he kept to himself that week a lot.
We have since found our own house and moved in together and it's been great. Until he bought weed the other day and is now smoking it. I personally have a zero tolerance for any drugs so this upset me a lot. I have 2 little kids and we r getting his son and I just want none of that life style around. He was adamant that he needed it for anxiety and it helped him and I needed to lay off. Since again I know nothing of heroin withdrawal or anything I dont k ow if that's true. He is on suboxone. But when he comes in high after smoking a joint, it honestly makes me so mad that its pushing me away from him and I need to know if this is something I need to accept or if it really isnt good for him to start again. Also my own anxiety is through the roof because he has court again this week back in his old town. I dont think it's safe for him to go back and I'm very stressed about it. I'm supposed to babysit my sisters massive dog while they go for a weekend away and also have some friends coming to camp by us. I really think I should cancel my plans even though it would screw my sisters plans just so I can go with him. I told him that and he said he didnt want my 2 year old coming because it's such a long drive and she freaks out in the car. She does and it's terrible. So I just dont know what to do and I dont understand what happened before. Any insight is greatly appreciated. Thank u!

Thank you so much, I really appreciate this insight. As I dont know what signs to look for if he is using heroin again, I have become suspicious and it is harming our relationship. 8 can completely see your point of getting wrapped up in it and how that is not ok. Are there things I can be aware of of he does start to or is using again? Otherwise I guess I need to let it go and just be cautious. I will look into some books and websites. Since I posted he has let me know he is having court postponed until we can make better plans for me to come with such as the kids going to their dads. He agreed it wasn't safe for him to go alone.

@Justine Welcome to the site and yes you are in a tough situation,i feel for you and for him.I know both world's unfortunately from experience.I have been sober for...i don't really know exactly but somewhere around 4-5 month's and addiction sucks and recovery is a son of a bit×h.I say this because while actively using you lose yourself and it control's your life,and recovery your trying to find yourself and it can also control you however once a person breaks that threshold and becomes an addict it's at that moment we become entangled in one or the other and having normality forever becomes even harder.This does not mean we can't be good people in healthy relationship's but it does mean making our significant other aware of the truth and giving them the choice to stay or move on.I read he takes Suboxone and you are aware of that so what i would suggest is you learn as much as you can about Suboxone,read some post on this site in the prescription drug abuse section so you can have contrast to the good and bad from the substance.Suboxone as a temporary solution is good however the longer you take it it will eventually replace in this case heroin,meaning yes it can start to make you appear to be high as your body accepts it more and more.I am a firm believer in trust until given a reason not to and maybe that's because I'm a recovering addict myself but i don't know,however i do know that if he's not using the more you accuse him or question him the more likely he is to use so stop looking for something that may not be there or you could put to much pressure on him and it maybe a reality you help manifest.Now I'm in no way saying you would be at fault im just saying that being in a relationship with a recovering addict plays by different rules then other relationships,that's why i started this by saying it was his responsibility to be open and honest about where he was and you have to understand if he was you acknowledged and accepted thing's would be a bit different in this relationship.Being an addict and being with a recovering addict are both very tough thing's that even more than most relationship's have to be centered around complete honesty,understanding,and acceptance.The drive explains everything you thought you noticed and i imagine he was pretty stressed over the entire thing,and considering he moved away from his old life to start new with you and had to drive back,well that kinda sh×t gives recovering addicts nightmares so maybe the twitching and irritability you spoke of makes perfect sense and has nothing to do with using however i can't be sure im just saying it would mess me up for a few week's easy just to go back to where it started,so for your sake and his the best advice i can give is trust until you have proof not to otherwise your both going to hate life and grow apart anyways.You both sound like good loving people so focus on the good and stop looking for the bad,if there is bad you won't have to look for it it will show it's face all on it's own.I hope this helps in some way.Stay Strong and God Bless Take Care

You will be ok just stay open and honest with each other.

@True concern has basically taken the words right out of my mouth.
I know when I had to go to court and handle stuff with my son, and other occasions where I had to go back to where I used to use my family would be on me about was I good while I was gone and crap like that.
There is nothing more for me as a recovering heroin addict(who is taking subs btw) for someone to question my sobriety when all you have to do is look at how damn stressed out I am by just driving back to the town where I used to use.
I won't even ride there with someone because I'm afraid I might not be able to leave fast and others see6this as me wanting to be able to get away from them and use.
NO!!! It's not like that at all, but I see where there coming from given my many years of lying.
But they have realized that if they are going to give me another chance then they have to trust me. And I realized that I could get defensive way too quickly making me look guilty when I wasn't.
By the way, no heroin user would say we " just chased a couple dragons". That sounds like something someone made up who has never shot dope before and is trying to use some poorly worded slang.
Your"chasing the dragon" when you've been up for a long time and, often speedballing, and trying to get that first hit opiate high. I would tend to believe him.
Sorry reread, "did a few dragons". Nobody says that.
I really would give him the benefit of the doubt.