He doesn't love you. He's in love with the idea of you. Can you grasp the difference? Also, what's the deal with him already having a 4 year old? Is he divorced or, worse, couldn't commit to his baby-mama?
This guy sounds really emotionally immature, as hello said. Don't be fooled by his lovely-dovey romance. Its not for your sake, its all about HIM. As you found out after the first tidbit of reality kicked in for him.
I think you already know this guy is all veneer and no substance. You just needed an objective POV to tell you again. Oh, and I really admire you keeping your child away from him. Really responsible, great call. Good luck.
Second thoughts can generally be amended with judicious action; injudicious actions can seldom be recovered with second thoughts.
--Cyteen by C.J.Cherryh