NoCode, I am a child of divorce. In a very unusual situation at the time, my Dad got full custody. I don't know my biological mother, have never met her to my knowledge and don't have a whole lot of interest going there.
I probably don't know the whole story and maybe someday I will meet her, but from the letters she has sent on random occasions, I can't expect the truth. I feel deep down that I turned out a better person for being with my Dad. He was strict and over protective. I don't remember him ever talking about her either good or bad. Most of what I know of her came from my Dad's Mom.
My point is that you need to somehow make peace with your situation. It is not your place to condemn these people, GOD can handle that on his own if he sees fit. You don't have to love her, like him but you do love your boys and if you want to make a positive impact on their lives from here on out, you need to let all that cr@p go.
After they have been with her, just ask if they had fun and tell them that you are glad to have them this week, evening or whatever time you are looking at. Then be their Dad. Do all the things you love to do together. Show them what the high road is.
Hugs, kat
Me-53(and learning!) S24, S21, D18, D17 Just keep swimming, Just keep swimming. Dory