Not sure how anyone can spy on you if you delete browsing history or they look over your shoulder. Personally speaking if your R is going down the toilet you need to address the issues. You will need to explain your sitch in much more detail.
I know it sounds alien. It is. However, the people that can help you need to know more to help. Why? Because they can see patterns in behaviour - sadly we all follow these patterns. But if they can't see all of the patterns they can't help you with them. Your W is also following a pattern. Perhaps that of a WW???
I have read your sitch and there is a lot of so similarity to mine.
Both drinkers - me more in fairness she is more pleasure, stressful jobs etc also. Curbing this is your key change. You W might not curb her drinking, gong out with the girls thing for a while but ignore that. Just focus on being the perfect version of you, reliable great dad etc.
My W had an EA with a guy, possibly PA, WS often accept the lowest level of waywardness only. And often after you discover it - why would the broadcast it.
The bile and spew you have had, divorced friends and wayward party girls. Had it all. Was building for years. My W surrounds herself with people that validate her wayward behaviours because she knows it is wrong. But she can't help herself right now because she is lost.
You have to become the shining pillar of you. You get found first. She then can see that and see she the mess she has got into.
You will have seen lots about detaching on here. Sandi and other make it really clear. The reason you do this is to protect yourself from her actions and words. You also give space for the same reason to some degree. But also, she needs it. This gives you time apart as time together bumping heads is going to make things get worse. Every time she sees you, you will bring up those feelings of frustration. You need to cut that so she can see you again.
Detach and give her space is great advice from Cadet, Sandi etc. Focus on this. Don't know what you do to destress, run, read, walk, cook, post on here.....they all help. If you do this, soon you will start to see the anxiety go (it will come back in shorter bursts - grief cycling) and you will see the core you again. Because sadly, you kind of get a fog too and yours needs to clear.
Detach, give space, be kind, exercise, eat, sleep etc and take care of this kids. Be the best daddy ever. Keep posting. Open up - people on here will only help. There are no other agendas. Delete browsing etc though.
Take care.
Surfer.
M46/W40/D8/S6/T20/M12/Separated 6/2016,W takes kids Issues2009 Wpartying w/g.f's2013on EA2013PAdeniedWleavesMBR ImeetAP/EAhalts VariousBDDates MFCourse WSpew EAresumes I halt Wrages DBIng4/2016