What should I do? Need genuine advice.?

This is not going to work out. For a start he admits that he would choose the other girl over you!! well does that not tell you something. Now there is far to much hurt between the both of you and you don't trust him really and I couldn't blame you I wouldn't trust him either. All this apologising isn't good but why do you bring this other girl into it when you argue? You are far to hurt so please move on and give yourself a chance to get over him and find someone else. You will always have baggage if you stay with him and the last but most important thing is he left you when you thought you might be pregnant what kind of a guy is he. Have his unpretected with you then scarpers OH come on get some pride and back bone and move on