I have a very close (platonic) relationship with my daughter's ex-boyfriend! Help!?

Everyone tells me that I have to stop seeing him and talking with him on a daily basis but I love him like a son. I can't imagine telling him that I can't communicate with him anymore. Of course, I love my daughter but we are not on good terms at this time and she has moved out to live with a girl-friend. I think I'm sad and depressed about that and I find comfort and companionship with her ex. I don't know what to do.