What Can I Do as a mother?

I was with my babies father for 2 years, loved him more than anything.. All he did was cheat, I am now 19 weeks pregnant with his baby..I am 21 years old and he is 27... We split up just before I found out about being pregnant because he decided he wanted to be on dating sites instead. A week after I told him I was pregnant with his kid he got back with his girlfriend who is 19, and now today he told me that she is also pregnant now and I am absolutely devastated.... I do not want my child to have to be with him, his new girlfriend, and their baby... I know my child will be treated differently... oh man, I have so much running through my mind right now and I cant stop crying, I know the stress is bad for the baby... it seems like he loves making me hurt! Sorry for the rambling but I guess my question is... How do I move on and get over this and be happy about my baby?!? I am trying so hard but I keep having the "what ifs"