Steve, it's great to know things are getting on track with you.
As far as my D16 goes, I am getting dumber every day. Not getting dumber as fast as I was last year, but I'm still the dumbest person on the planet. Really, though, I think they are just all asserting themselves a little bit. I let mine know she's not entitled by taking the phone away, or not driving her to a friends, not giving her money for a movie, so she's more appreciative when I do, and it works pretty well. Especially taking the phone away....
Anyway, I think this is all very normal. D16's dealing with her parent's marital issues, too, and it's much harder on her than I first thought. Plus she has all the normal teenage angst.
Do you ever just take her out for dinner? That's something D16 and I enjoy, and it's nice to be able to talk without the usual distractions. (No phones at dinner!)
M:23 T:26 Me:53, Wife: 60 S:18 D:16 filed 7/16 W moved out 4/28/17