Struggling with my relationship anxiety

Hello all. So, my fiance and I have been together for almost three years. Recently, we have been having a tough time. A couple days ago we got in a horrendous fight and he was ready to leave me as he could no longer deal with my anxious behaviors ruining our happiness. We spent two days apart but ultimately decided to have me come back and try to fix things. We were suppose to be getting married next month but he has decided it is best for us to push our wedding back to the Spring now and also to wait to start trying to conceive as we had been until after we are married. I get that he feels it's important to focus on rebuilding us right now but I still feel very hurt and like I lost so much. We had been doing good the past couple of days once I got back but then I got anxious and admitted to him I was worried about him turning back to using drugs. He is an addict, and has been clean since January but is friends with his dealer and he called which triggered me I think. He basically told me I have to stop getting triggered by that and that he cannot promise me there will never come a time where he relapses. I told him that I just don't want anything to happen that ruins our relationship and he took this as me saying that instead of trying to help him if he relapsed I would just leave him without being there for him. And then he abruptly cut the conversation off and said "that's good to know." I feel like I have messed everything up again. He has been being nice since then and still talking to me and saying love you and everything, but I am such an anxious wreck that I have destroyed us fixing things. I told him we were on a good path and I don't want to ruin that but he said "it's only been a couple days. We can't say we are on a good path yet until we have more good days." So 1. I am scared I blew our second chance at fixing us by getting anxious and telling him the truth about why I was anxious. I created a problem out of nothing as I always do. 2. I am afraid he will go back to drugs someday and I won't be able to go through that again. 3. I feel sad that we pushed our wedding back and he wants to now wait to try to have kids. It feels like it was taken away from me when I had it for a couple months. 4. The drugs scare me because of his health, but also I am very afraid we will never have kids. We have a significant age gap and he is 40, previous steroid user, previous drug user, drinks and smokes and it just seems like there's no chance we will have be able to have children. This scares me so much because I value having a family someday. Now we are pushing it off for who knows how long when he's at an age where each year counts. 5. I want to be with him and be happy, I'm just so afraid of messing up again and him walking away like he was going to last time. I want to feel like I am wanted and loved, and I don't want my anxiety to ruin us again and this time permanently. But I also want to know we will be able to accomplish the future we talk about and I am scared of getting hurt or disappointed for so many reasons. I just feel like at any second he might decide that my anxiety earlier about the drugs means that we cant fix us and he will make me leave again when I just want him to want to work with me and have a happy life. I don't know what to do and there is no one I can talk to about it.