HELP! My bf talks to and hangs out with his ex more than he does with me?

I feel like my bf is making me depressed. He swears up and down that he loves me and there's nothing to worry about. I told him that i really don't feel comfortable with him seeing her and he just calls me insecure and jealous. He goes to lunch with her and babysits for her and it drives me mad. We've barely spoken in over 2 weeks and he ignores my facebook messages but responds to hers. It makes me feel so low and so hurt cuz I love him completely. I asked him to stop seeing her but he says he won't give up an 8 year friendship for an 8 month relationship and if I loved him I wouldn't ask him to. But all I seem to do is cry now and that's so not like me. I can't have one conversation with him without us fighting and me crying. Am I wrong to ask him to give her up for me? And if it matters the reason for their break up was her cheating on him and they dated for abut 6-7 years and we're engaged. I'm 19 he's 25 and she's 22.