Search Results: messing around with her boyfriend

I'm in love with my best friend (she's a female) of several years (and it took a few years for that love to develop). She had a boyfriend for much of the time that we've known each other and for about the last year I've known that I can't be just friends with her and can't stand to see her be with someone else or get married. We've been messing around for a little while but she said she doesn't have feelings for me in that way, although she does sexually.

I honestly can't put myself through that again, it tore me apart for years to see her with someone else and I can't do that for the rest of my life, but at the same time I can't stand losing her as a friend and it will absolutely devastate her, especially being that she's at a really low point in her life right now. Does it make me a jerk if I have to walk away from her?

Additional comments are always useful.