You obviously can't make yourself be friends with someone. There's nothing wrong with reacting emotionally, since friendship is a very emotional thing. I agree with lead, that you should explain your reasoning once, calmly as possible, and then break your ties.
I've had to break ties with a friend because I finally realized that we were in totally different places, and that she was starting a downward spiral that I couldn't help her with.
I think you've decided that you don't want to be friends, and now you just feel a little guilty? Well, let them find other "friends." They don't need you, and it sounds like you don't need them. So drop 'em like a hot potato!
