[AmberS9109]

You need to know, that him leaving was in no way your fault. He's a coward. He's leaving because he doesn't know if he can handle the responsibility of a child or he just plain doesn't want to.
But you have to realize, that even if you do want to make things work with him; you shouldn't have a guy in the baby's life who can just walk in and out when he feels like it. You have to put your foot down and say "Hey! Either grow up or get out. This is our baby, and if you don't want a part of his life, fine. I can give him all the love he needs!"
I hope I helped a little, and good luck with your pregnancy