They pick a fight before doing something non-matrimonial. They work themselves up into an anger so that in the moment of anger THEY feel justified in doing something that they KNOW is not nice to you. In this case it would be your Starbucks conversation close to the weekend. You saw it as confusing, out of the blue, and mean. He saw it as you fighting with him (which he instigated!!!) to justify his next behaviour (weekend with OW).
When I look back at my WH, I realize that we had fights almost every time before he went out with, well, whomever. Sometimes I didn't even engage in the fight, it's like it was just spewed out at me, and then off he went, indignant and all. It is WRONG, it is SELFISH, it is really CHILDISH behaviour, and there is nothing you can do about it. Watch for the fights and you'll be able to predict when he is seeing or trying to justify these behaviours. If you know OW is in town, anticipate that he will do this, and don't engage AT ALL. One more reason why it is important to DETACH, do not give him the satisfaction of justifying his behaviour. Don't fight, don't validate, don't anything.
I know it's hard. I had a big fight with my WH on Friday, it just built up and I needed it to let it out.... and I'm sure it's justified his taking my kids all long weekend and taking my extended family away from me, and and and.... time will help heal me.
More on the rest later, if I can think of anything helpful.
