I don’t understand why life is like this

I’ve been with my husband since high school. I got pregnant in high school and had our daughter who is now 15. Things weren’t that great back then but we’ve stuck through it and been through a lot. We were doing great for a while but the past 4 years have been the worst. I had been wanting to have another baby for a while because I didn’t want our kids to have a huge age gap. We had to wait a while to try until we had a house and were good financially. It took a while once we started trying but I got pregnant in 2016 but ended up having a miscarriage at 10 weeks. That was devastating. We kept trying again but it wasn’t happening. I was pretty depressed and crying every month because of not getting pregnant. That’s when I noticed a change in my husband. He was acting crazy, cursing, angry, loud and just not himself. I figured it was drugs and told him it was unacceptable. He denied. Things got bad at times and we would leave and go stay by my moms. We’d stay for weeks or about a month. I think the longest was 2 months. This happened a few times but he always promised change and my daughter always wanted to go back so we went back. Eventually he admitted he had a problem. I forgot to mention I had gotten pregnant again in 2018 and had another devastating miscarriage at 11 weeks. He didn’t admit his problem till last year. He had told his boss and was talking to a professional who dealt with addiction and detox. His problem was prescription pills but started taking suboxone to try to get off that. Anyway he got a lot of time off work and was home detoxing and extremely sick for a while but I so excited to finally have my husband back. His whole attitude had changed. Stupidly I decided to try getting pregnant again and this time it worked. I now have a 6 month old daughter. My husband was doing good for a while but started messing up again while I was pregnant. It became a once a month thing. It wasn’t nearly as bad as it used to be but I can’t tolerate any of it. Well once he was still being like this after I had my baby, I had enough and so did my older daughter. We went by moms yet again when my baby was only two months old. It was hard. I was still struggling with how to take care of a new baby and now I didn’t have my house, her stuff and dealing with my emotions of not having my husband. This had been my dream for years to have another baby and to have my family complete. I would bring the baby over there to see him and of course he was normal every time and I missed him so much and felt like he was missing out on so much. My older daughter hated him though and doesn’t understand why me being pregnant and having a baby wasn’t enough for him to change. We ended up going back 3 months later and things were really good for over a month but then he had a couple off days. He wasn’t horrible but I can just tell he wasn’t himself. He was very talkative and just a different personality that I don’t like. I honestly don’t think people who don’t know him would even notice but I notice every little thing and so does my daughter and she wants to leave again because she says it obvious he’ll never change. I’m not going to lie but I feel that way too but I love being home and a family. All my baby’s stuff is here. If I leave, I’ll have nothing. I hate that he’s normal most of time. It messes with my head so much. Life is good and then he ruins it. I literally get nervous every time he comes home wondering if he’ll be normal or not. If he seems off I get so much anxiety and feel nauseous and can’t eat and my stomach gets so upset and Im breastfeeding. 😭 I can’t live like this. Anyone have an explanation of how he can go a whole month without anything? I really don’t understand that part. What should I do. I feel like life is so unfair. I could’ve been almost done with him since my older daughter is 15. Now I’m stuck with him for 18 years and have to worry about him getting my kids on weekends or whatever. I know I can require drug tests but I know he knows ways to get around that. Thank you to anyone who took the time to read this. I feel so stupid and like I’m such a bad mom because of this. But my kids are my life and there’s nothing I love more than being their mom. Sorry this is a little all over the place 😟