In a relationship for 6 years, my husband keeps having fits every 3-4 months threatening divorce and other?

I have been with my husband for 6 years, 5 of which we have been married. When we initially broke up he moved back home to New York well two months after he moved home he said that he missed me and he wanted to come back. He came back and we got married a year later. About three years ago every 3-4 months he goes through these little mood swings and tells me what a horrible person I am and calls me every dirty name he can think of, and tells me how miserable he is here with me and he just wants to leave, he is having one of his little fits as we speak and has now told me that he is not attracted to me anymore but throws in and I quote "I am his best friend and the last thing he wants to do is hurt me",but he has been thinking for two years how to file for divorce. I have tried to give him the easy way out and give him divorce papers and he just gives them back to me and tells me that divorcing is not what he wants and he doesnt know what he wants but it's not that. When I get upset with him for the things he says to me and bring it up to him he turns it all around on me saying that he cannot talk to me and I just dont understand him and I always misunderstand what he says. How can you misunderstand someone calling you names and telling you what a horrible person you are and telling you that they are not attracted to you. I want to be a strong independant person like I was when we first got together but I feel that he has taken that away from me. I certainly dont want to file for divorce because I think that his feelings are just growing pains which I know are typical but I need some advise. Should I keep forgiving him and just keep hoping that things work out like they always have or should I just distance myself and prepare for an eventual split up. I just dont know what to do, I am tired of him hurting me and then saying it's my fault I just misunderstand and he loves me more than anything in the world and I am his best friend, if i was all those things then why does he constantly act like this, and when I try to talk to him and get logical answers alls he says is that he doesnt know what he wants to do he just doesnt know.