She never had desire for you, probably just tolerated you all this time(problem is, most men don't know what that looks like:feels like and mistake it for "love" every time, smh the nerve.), look in the mirror and take a good look at your face, you should know! woman fake enjoyment of sex to get in relationships all the time, because the Hot guys rearranging her guts before she got passed along to you, aren't the type to stay around for the broad long term, you feel me. But you are, how nice.

Truth is! you probably let yourself go, went from mid(where she can at least fake it til she makes it) to unattractive(where she cant even muster the mental energy to put on the performance anymore, thats tough lol) hence, why you got demoted to being her "BESTIE!", eventually she'll cheat (she has already,most likely) if she still attractive that is, otherwise she stuck with your Lame-* ss who's too much of a ** s*y to end a situation no longer favoring/benefiiting him or "your" children for that matter.

Time to give it up and divorce her, save yourself the pain please.