Well topgun, your sitch isn't substantially different than many others on here. If you read DR then you probably know what works and doesn't work, but in a nutshell do not beg/ plead/ negotiate/ go for sex/ try to fix things/ push for marriage counseling/ etc. Read Sandi2's 37 Rules and live those tips!
As for what does work- own your problems and do 180's on those things. Give your W time and space to sort through her own issues. She does seem to have at least a touch of MLC with all the partying and such, but then again it may just be coming from her new sense of "freedom". Many WAS's will engage in behavior like this but then drop it after several months to a year and revert back to more familar behavior. It's part of their journey in finding out who they are and why they are unhappy.
Speaking of that journey, they must make it themselves. There's nothing you can do to help them or speed them along. Just make yourself into the spouse only a fool would leave and have a lot of patience with your W while she goes through her journey.
