You just have to face the facts, the sooner begun the sooner done I suppose, although that obviously isn't the aim when you are trying to save a marriage or a long term relationship but some just can't be saved due to the attraction issue. I expect most people did the same thing I did, try to communicate, try to "see how it goes", see that it isn't going anywhere and then slowly evolve into some other kind of relationship organically whether it's what you desire or not.
I became a lot more cynical in the process, since I had to face the truth that love can't solve or fix everything, and love is a biological thing with sexual attraction, not a choice. That's a tough pill to swallow for someone whose life experience has never been as straightforward or easy as "I like X, I get with X, I am happy" but I had to take it anyway. About staying friends... that's just in the character of the people involved. If you had mutual respect and respect for each others' values and boundaries from the start it shouldn't be a problem. If they or you have to have a sex life then you're going to have to work something out and probably drift apart. I didn't need that and neither did the other guy so there wasn't much of a need to immediately move out and start dating and stuff. There's things I want to do with my new found life before I even bother getting into all that again. It was basically going round in circles only to end up where it as predicted we would so I could have saved myself the trouble and just relaxed and watched it unfold. But it took a couple of years for the pride I had in myself and the investment I put in to shrivel up and die and just accept it. Pride makes people do and say some pretty stupid things, eh.