You found a good place to Vent and get some advice and 2×4 we tell you the truth. So here is my thoughts
I was never the one to confront OW to me it wasn't worth it. I expected W wanted to fight for her. Not... I was like you I have grown mentally and I know my worth. I know I am a dam good W and mom.
So this is your coworker right. Many would say contact OM wife. Call him out on his crap. But many will also say No let her do her thing and GAL
So only you know what's right.
But most importantly you must protect your fiance. Your W not working take W name off Credit card. You don't have to even tell your W. I didn't tell my W my credit cards W was just an authorize user, W monster on how embarrassing it was getting things in store and when W went to pay it was declined. Yelp declined. My thoughts where hey you acting single you say we are not a couple so this is what couples do.
Trust me true colors and monsters will come out. MlC or WAW like to spend on OW or OM.
So keep doing you keep protecting your kids and your finances please Handle that.
And again if you feel is right to contact Wife of OM then do it you have the proof.
You seem like a nice guy. Is time to not be Mr nice for now...
Remember lots of rest, eat well, take care of yourself so you can be even a better version of yourself.
At BD Lesbian marriage Me39,W36 S9,D9,S8 adopted all three Together almost 10yrs Bomb Drop - April 2017 W movedout - May,2017 OW June,2017 Currently 2018 Me40, W38 S10,D10,S9