John, Congrats on having a good dday for your bday and it is important that your daughter enjoy your day as much as you do...
Exactly what Puppy said X2...to include giving up that apartment immediately...if you back down and give in now this will happen again if it even ends. Remember right now you are in the best postition you could possibly be in if you have to be in this position...wife gone, left her daughter, multiple affairs, paying all bills...remember, don't set yourself up for another heartbreak...she has done this and will do it again...and if she comes back you can bet she will have moments that she expects you to put up with anything she wants...no life for anyone.
I have to agree with PDT again, she is a liar and until she actually does something do not believe anything she tells you...perhaps she is starting to get low on money right now, make sure the bills you think she is paying is being paid. OM might have a guilt trip (I doubt it) after his visit home
Keep investigating, I doubt you have seen a lawyer but you really should post-nups are enforceable...write one up that covers adultry...
Exposure is still your best tool to end this affair...she is not going to end it just because she has seen the light and is reborn...doesn't work that way.