you can let her vent IF it's at all productive. Do not defend yourself but simply say
"if I had it to do over, there are lots of things I'd do differently" and that does not escalate.
It also shows that you CAN and WILL change (perhaps for another woman. And that will bother her b/c then you'll be a great catch, etc)
but if she makes things up or believes them but YOU DO NOT, then say "wow, that's Not how I rememeber that at all, but I'm sorry if you were hurt."
Then REPEAT the line about how you'd do "lots of things differently if you had it to do over again"
but not that you are asking to. Do NOT pursue her.
Most importantly do not let her disregard the custody issue and use your son as a pawn.
He needs you as much as you need him. Be true to HIM and do not let her keep you from him. It's not about keeping peace with her at all costs. It's about being there for your son, at all costs.
Make sense?
I happen to think, in the long run, it will help both relationships if you make time with your son the priority.
But if you must choose, choose him.
M: 57 H: 60 M: 35 yrs S30,D28,D19 H off to Alaska 2006 Recon 7/07- 8/08 *2016* X = "ALASKA 2.0" GROUND HOG DAY I File D 10/16 OW DIV 2/26/2018 X marries OW 5/2016