@xxtatar25xx,
So let me get this straight. You are living with the mother of your child and yet you claim to be still in love with an ex whom you split up with a while back and who has now reappeared and is willing to come between you and your child's mother because the two of you are in love. And you don't want to just ditch the current girl because she will have no place for her and the child to go (aren't you a nice fellow.)
Other than the obvious RIGHT answer which is for you to forget about this other woman and at least TRY to make a go of things with your child's mother, there is one other thing you can do that would at least show you are taking responsibility for the child and not throw mother and child out.
Why don't you just move out and continue to pay rent for this woman and your child? Then you can at least soothe your mind by believing you did the right thing. They will have a roof over their heads and you will be free of actually having to live with them. After all, any family court is going to make you pay thru the nose to provide for them anyway, so why not get ahead of the game and look like a really good guy.
Of course, you could also choose option three. Maybe the ex would be willing to move in with you and the new woman. Then you won't have to kick anyone out.