Pregnant & BF has been cheating on me

Yesterday I found out that my boyfriend has been cheating on me with his ex girlfriend that is actually married. I only found out because she saw my facebook and a post that he bought me a pair of shoes so she sought me out and showed me all these texts between the two of them and he told her that he loves her and everything. Im 13 weeks pregnant with his baby. Im completly devastated. I made the mistake of being completly reliant on him. Im unemployed and I have been for a long time.now. Im a recovered heroin addict ive been clean for only a little over a year now so I was so depressed and I also had really bad morning sickness so I was just kind of moping around which is not what I want to do with my life anymore. He actually told me he needed space before I found out he was cheating and he said it was because I dont make him happy because I just lay around all day everyday. But that really isnt who I am. Ive jusy been struggling after doing drugs for so long and now being sober its like I have been lost. Hes a recovered addict too but I guess im just weak. I cant believe he lied to me and said it was my fault. We were supposed to move to a new apartment together this weekend and he was going to move the other girl in instead of me. I feel so dumb. Im so broken right now and im very weak mentally. I left last night because i was crying so hard and he told me to come back because he didnt think it was good for me to be alone like that. so i did go back. And i cried so hard for so long and he held me and that eventually turned into sex. idk why I did that. I truly love this man and IDK what to do. Im so lost and I just want to get high so I am numb but im not....I dont see how im going to move on with my life and get a job and move into my dads. I'll always be wondering if that girl is with him at his new apartment. I dont see how I will be happy for a really long time. I haye being alone and now I have to move into my dads house which I really really dont want to do. Please someone...I can really use some advice.