Not much you can do about it unless your W will listen to requests.
D5 has been overly emotional.. constantly saying she wants us back together.. wants to spend more time with me.. see me more.
W is constantly either on the phone or with OM.
Detach.. Detach.. Detach.
All I can say. It's for your own protection. She's not your W right now.. she's someone else.
You also mentioned the going out all the time thing as well. This is sort of like a MLC. My W is doing the same things. I get what she's doing.. she went to college, quit before she finished and was pregnant with D5 before she turned 21 (actually turned 21 while pregnant). So.. she's "figuring out who she is". I believe that's kind of hard to do when you are shacking up with someone else.. but whatever.
I'm confident one day she will look back on all this and realize she made a TON of mistakes.