Terapin, welcome back and sorry you find yourself here again.
I agree you have reading to do. Obviously, you have to decide if you want to save your marriage. But I'm sure your son is why you are considering trying. And that's admirable.
As far as her swearing on your son's life, I don't buy it. My wife would have said anything rather than to admit that there was someone else. So I'd move forward assuming she's at least in some stage of another EA. And then proceed accordingly.
By the way, this is a very common tale. My first situation in 2005 was similar to your situation 5 years ago. We didn't deal with it and 12 years later same thing over again.
The good news? You, like me, knew about DBing so you could start DBing right away! Most LBSs come here after weeks, sometimes months. So if you do want to save it you're at an advantage.
We're here for you!
M(53), W(54),D(19) M-23, T-25 Bomb Drop - Dec.23, 2017 Ring and Piecing since March 2018
