Validation and boundaries are two separate issues.
Never validate a bad behaviour or poor performance. Completely inappropriate. Be neutral.
Validate and acknowledge feelings not thoughts or behaviours.
I would not validate in this instance. I used to foster teenagers and often enough parents would fail to fulfil their promises. It is worse to cover for it as that contributes to the smoke and mirrors, it makes you appear complicit and flaky. When you make a promise it's rock solid isn't it? Your children can take it to the bank? That's enough, then validate that WH promises aren't worth much sometimes. That is reality.
Quite simply it is a boundary issue about not sticking to the parenting plan, problem is you need to enforce the boundary which you can. Although it may not be worth the effort, just shrug it off.
Your boys are old enough to have an R independent of you with their dad and you can leave them to it. Get out of the way.
STFU on OW being in attendance as otherwise you may be accused of 'spoiling' the soup. Let reality bite for WH.
I would consider not getting in the way and not compensating for WH losses.
It isn't your job to cover for WH. If he promises and doesn't deliver then he doesn't, his loss. It is up to him to advise the boys, tell him so and don't cover. If he lets them down at the last minute he should tell them himself.
I would make that your boundary and get out of the way.
WH have you advised the boys that you have cancelled? In future you can deal directly with them on activities, as long as it fits with the parenting plan you can arrange activities with them. Just keep me in the loop. The boys are old enough to deal with you on activities you arrange in your parent time.
The modus of your WH sounds like devaluation and discard. It runs deep and likely to be personality driven.
It is my view he doesn't want to marry OW, she is just a convience or resource for WH. If you D him, which would be my very strong suggestion to firm any fins and parenting plan then WH will have little choice with this OW. He may devalue discard and move on, it's his history.
OW are always affair down, so it is likely WH will move on. At least this one has resources ie cash.
Just my 2c worth
V
Freedom is just another word for nothing left to loose. V 64, WAW
