@Bboo3 I’m so sorry he’s being so selfish. It’s not that you’re missing the point of the break, it’s that you’ve seen through him and know precisely why he wants the break and don’t like what you see. And clearly his lack of care for your children wrapped up in all of it. If there wasn’t another woman involved, I don’t doubt you would be supportive of a mental health break if he needed it: you’d likely have discussed it as a couple and helped him make arrangements for it. But this isn’t that.
If he had responded in a more positive, conciliatory and apologetic fashion to you telling him to come back or ship out, if it had made him acknowledge the enormity of what he was risking by behaving this way and he wanted to come back and seek a way through things, if he had even agreed to couples counselling as a way forward… I and others would absolutely be supporting a decision to try and work your way through it. But all I see in him is yet another selfish bloke who seems to believe everything revolves around them and their needs and, when confronted with the needs of his wife and kids, throws a tantrum instead of engaging.
He may have rationalised to himself that whatever he is doing this week is OK because “you’re on a break” and therefore somehow thinks that you should be fine with that and feel grateful and honoured if he picks you at the end of the week instead of holding him to account. He’s missing the point that you’re his wife and he should have picked you every step of the way, rather than starting something with another woman. This shouldn’t even be a question, yet here you are.
So yes, you’re spoiling his week of guilt-free self-indulgence, because he can no longer escape thinking about the consequences of his own shitty behaviour. Most importantly, you’ve taken back control. You can keep that control.
Maybe at the end of the week he does work out that he’s been a total fuckwit and owes you a grovelling apology and a serious commitment to working through the pain he has caused you and going to couples counseling if he wants you to take him back. But you get to decide whether that is what you want and, if so, what he needs to do to earn your forgiveness. And he has to commit to the process and understand that you can’t just get past the betrayal because he says he’s sorry.
I don’t doubt that you will be OK without him if it comes to it. Better than OK, because I suspect that throughout this week you will find life easier without him in ways you’d never really considered and, even if you miss the man you married, may decide you don’t miss the man he’s become quite as much as you thought.