Hurt: We don’t tell people struck repeatedly with bats to “get over” feeling hurt.
I don't think you necessarily harmed yourself by making the old agreement. You read the situation, saw that you wanted your husband in your life and your mother-in-law out of it, and found a mutually acceptable way to have both.
But even a deal or contract that was celebrated upon its signing can need updates. Circumstances change, people evolve, wisdom accrues.
And injured people heal, get stronger, find their voices. You dealt with your in-law problem, then you took care of yourself, now it's time to reckon with the problem of your husband not standing up to his family. Not standing up for you.
The time for that reckoning wasn’t “then” or “before” or even “now” — it was always, when you were ready.
What made sense when you struck this deal with your husband made sense to someone who was fighting for life. You needed your husband’s support for creating a mother-in-law-free zone, and he rightly gave it to you. We can all appraise this situation now and say, “Wow, I can’t believe he still hung out with his family and you were okay with it” — but that’s because none of us is living the reality you were living in then. You did triage and secured the equivalent of emergency measures; he joined you in this effort not just as your husband, but also as the child raised by a bully in an environment created by a bully.
So that first agreement was a lot for you to manage, and a lot for him.
You probably have been in a position for a while to recognize the need for an updated agreement. The mother-in-law is gone, you're stronger, and these two changes point directly to your having greater perspective than you did at the time. Much. But it took the direction-change (and the huge ask) of a week-long vacation to wake you up to this, to call your attention to how truly messed up it is that your husband hobnobs frequently with your mother-in-law's (apparently) unrepentant, unindicted co-conspirators.
And although the wounds are shallower than the ones your mother-in-law used to inflict, these visits still injure you — you’re awake enough now to see that. So wake your husband up, too. As always, if you hit an emotional wall and if you have the means, seek solo or couples’ therapy for these talks.
You made the deal that was workable at the time; now it’s back to the table to negotiate terms that reflect what you now comprehend. Standing up for yourself has always been the best way to see clearly whether others stand up for you.