"I want my son to have his dad in his life......."
Well, dear......It seems his dad isn't in his life already if he is only coming over once a week and plus he isn't helping you with nothing. Of course he is telling you "he loves you"......he wants the sex. In reality, you are already alone.
Have you talked to him about this? If he refuses to change I would establish child support and end the romantic relationship with him. You are better off without him. Dont' keep sleeping with him.
Sorry to hear that.. Us moms tend to be needy during pregnancy so it does help to have the fathers support.. Have u talked to him about it? if that doesn't change anything than your better off alone but still co parent he needs to help with the baby n help provide for he/she.. goodluck.