open marriage? divorce?

hey all! i know that it's been a really long time since i've been around, but when i started struggling with this, i knew this would be the place to go. so i hope you don't mind me flooding the boards all of a sudden. okay...here's the problem: when i married my husband, i was over 400 pounds, so i was more than okay with boring old sex. now, i'm a complete freak, and well...he's NOT. we're not into the same things at all. hell, i can't even get him into french kissing - it's a real nightmare. *sigh* i've had a couple of affairs, but nothing really seems to phase him. we started marriage counseling a couple of weeks ago, but so far everything is absolute **** we've began discussing the idea of an open marriage, and i'm just wondering if any of you have any experience with that sort of thing? what are some ground rules that we should set if we do do it? is it something that could save a marriage or something that will definitely destroy what is left? i'm really lost here and could use any help or suggestions that you guys might have... ...and, am i alone in this sort of thing? any of you find out that you're no longer sexually compatible with your partner? thanks, ~k