From what you’ve said, it appears that your husband’s entire family treat him like shit, and yet, he still wants their love. That’s very common and very sad.
You seem to be looking forward to rubbing his nose into just how badly treated he is by them, by talking of revenge being sweet and planning not to go to his brothers’ 40ths, or other important events. Does your husband get a say in this? What happens if he wants to go?
When you have a child who badly wants to play with the other kids, but is always being excluded, you don’t deal with it like this. Or you shouldn’t. You find a gentle way to tell them that they are worth more than that and to find new friends, even though you want to kill the little shits for hurting your child. This the same.
This is an ideal situation for you. He doesn’t know anything about the event you’ve planned, so you’re in control of what he needs to know.
You could say: ‘I organised this thing but unfortunately one of your brothers couldn’t make it, but the others are going.’ If the others drop out, as you’ve said they might, then you just collect the money from them, leave your husband in blissful ignorance, and never organise anything for them again.
If your husband wants to attend a family occasion, then just go. If it’s the stag do in Vegas, then discuss whether it’s affordable or convenient.
At some point, it would probably be a good idea to have a calm conversation with him about where he stands in his family, with no talk of revenge and tit for tat. I imagine you’ll find that he knows, but it hurts too much to admit it.