Go back for baby?

My boyfriend and I have been together for two years and we have been living together for six months. We decided to start trying to have a baby almost immediately. I lost the first baby at 5 weeks. Around that time he started drinking excessively ( he was always a drinker but this was different) and I figured out he was messing with coke. I left him because his personality changed he got mean. I left before I found out I was pregnant again ( I'm 9 weeks now)...the next cycle after my miscarriage. Any way we have been talking and trying to spend time together. However he still drinks a lot even though he is supposed to be get help. On top of all this he admitted to cheating on me quite a few times in our relationship. Including when I miscarrying. Now I love him but I don't trust him. He's the only one that knows I'm pregnant again besides my best friend. I am scared to be a single mother even though I know he will take care of the child. Should I try to work this out or cut my losses and Co parent? It's so scary to do all this alone. P.s I'm staying with my parents while I figure this out.