Struggling with emotions

Hi, everyone. I'm new to this and feel uncomfortable asking for help but I'm getting desperate. I am currently in a relationship with a guy who is wonderful. But I keep bringing things from my past relationships into my current one. My last relationship was abusive on many levels. My new boyfriend knows about that and has tried to help me get past those issues. However, I still can't bring myself to trust him. He has never given me a reason to not trust him, but I still can't bring myself to. I am extremely insecure about what has happened in my past and the effects this has on the way my current boyfriend views me. Some days I'm okay, but other days he can't even put his arm around me without me flinching. I hate myself for this but I don't know what to do. Aside from that main issue that I know I just need to work on, my current concern is about tonight. He is going out with his friends and they will be drinking, and I keep thinking he'll do something bad or it will change his behavior towards me. I also have an anxiety disorder so this is only adding to my problem. I am so afraid of what will happen tonight and my anxiety has been horrible all day. I don't know how to deal with this. My biggest fear is that he'll find someone new who doesn't have as many issues as I do. I know I have to get on his nerves with all my problems. I just need advice on how to deal with this. Anything will help.