What should I do, I'm hurting so much?

Bf and I have been together 7 yrs and have a child who's 3. He moved out 6 weeks ago after an argument about him being at a party until 9 am and also heard he spent most if the night in the bathroom with a girl. I hated him at first but then started to muss him so much that I felt I'll. I'm at home with our son and all the reminders of him and he's living in a bedsit smaller than our bedroom. I've asked him to come back and he says he will but not yet. He says he's enjoying his freedom. He goes out every other sat night, and has our son one night a week which I think is really unfair. Our son is always asking for him and it's breaking my heart that it's so easy for him to hurt us both like this. He says he doesn't want to split up properly, but also that I'm free to do whatever I want. Then he says when I go out this sat he might come along to keep an eye on me! We've seen eachother a bit since he left and slept together a few times, and he's been doing new things which I know is a sign of cheating, but he said he saw it on some tv show. He also has a few scratches on his back that he went out if his way to explain to me. I don't even know if I would be able to get back together with him after he's hurt me so much, and it doesn't seem to bother him at all. He's always seemed to be out for himself, and extremely narcissistic. I don't know why I'm this upset over him, but it seems like he's just playing games/ lying and cheating. It's made me I'll and I've lost a stone since he left but he is just his usual happy go lucky couldn't give a shut self . I know if I was reading this my advice would be just to let him go and when he realises what he's lost don't rake him back. I feel so stupid. He said the other day me and our son are the only good things in his life, but he has no respect for me and doesn't seem to care that much fir our son