I find myself agreeing with pretty much everyone else in its time to drop the rope. If she wants this OM let her have him. She will find out really fast that she just lost the best thing in her life. I really think you should walk up to her and say well if you want him soooo badly then there you go. The Door is that direction and here are your car keys. Own up to the snooping and let it all hang out. It really can get much worse right now can it?
I have read a lot of your sitch and think wow she is lucky to have him she even realizes that she is lucky. I just dont get the mentality that you have to have to do this. Anyway just my 2 cents. keep your chin up, becuase things will get better.