All I can say, TurtleGirl is that the advice here is spot on. I'm convinced that your M has the best chance of surviving this EA/PA if you can follow DB principles.

When my H had an EA/PA in 2004 (just after the death of his mother), I followed this advice and he came back. A couple of friends had their Hs who left at the same time. They didn't follow DB principles and are both divorced now. They pleaded and pushed and it got them nowhere.

I backslid and my M is in trouble again but I know what worked last time.

Keep posting and reading stuff here. You sound as if you're thinking about this quite rationally. Good luck.

Me: 51
H: 52
T: 23 yrs
M: 19 yrs
S18, D16, S14 (special needs)
PA: 2003/2004
Piecing: 2004 on
Suspect H had EA: 8/2012-12/2012