Update to FMIL inviting cousin to be groomsmen on fiancé's behalf

This is an update to my previous post here.

Since my fiancé messaged his toxic cousin and his mom clarifying who his groomsmen will actually be, his family seems to have just pretended he didn't say anything at all. His mom actually texted on New Year's (after she knew we were stuck in traffic for 11 hours trying to go home in time for Tuesday classes/work) complaining: "Do you not have any more time to even text us? You're too busy now?" We had 2 long calls with her last week! 1 call was all him, the other was both of us. Fiancé told her again to not assume things and be passive aggressive, especially since she knows why we did not text for a few days and never replied to us about overstepping in the first place.

Fiancé also reminded cousin that he needs to make things right with me before things can even begin going back to normal for the 2 of them -- despite what MIL might have suggested. Cousin simply says he's already followed me on IG and that he has had anxiety for the past half year. Fiancé says he's sorry that cousin has anxiety, but no one should use anxiety as an excuse to be a crappy person who hurts others and refuses to make amends for it. Also, the cousins and other family started all the toxic behaviors last Christmas, so it's been a year. Cousin still didn't actually respond to the text about how he is NOT a groomsman, but we're positive he knows. We told the rest of our group so they'll know to keep him out if he tries to act like a member of the wedding party.

Of course, MIL hears about this and tells us we need to be understanding of people who have anxiety. This was the series of interactions that eventually made us both consider no longer being open to them making amends anymore since the time has passed. MIL and cousin knows how much anxiety the whole family caused ME through their threats, rumors, harrassment and how Christmas became a traumatizing time after what they did. In response, MIL says the cousins are just jealous because fiancé and I have our independence (masters degrees, job/med school, our own apartments), while cousins don't. Starts complimenting us, but I think that she was just trying to sweet-talk so we don't cut her off?

Anyways, my fiancé has since started therapy himself and realized MIL has been manipulating him his whole life to comply and not speak up for himself. A fewer commenters on original post said his family was doing all of this to hurt him and reign him back in, and he has realized that too. Ever since middle school, he was guilted by his family to not hang out with his friends as much because it will make them feel less important. If he told them way in advance that he had plans with me or friends, MIL will last minute want to go to dinner and ask him to reschedule, or ask to tag along if everyone knew he wouldn't cancel on me. If he insisted, MIL starts crying and FIL tells him he needs to comply because MIL provides for them all. Fiancé did not fully see all of this until this year so he apologized for being ignorant, thinking they were just eager to spend time together, and not warning me that there were two sides to his family, especially since the worst side didn't come out until last year but evidently was there all along.

We will get couple's therapy soon once he is a bit more back on his feet. All of this makes me sad because when they're not in the picture (such as after we went NC to the cousin for a long time), everything was great. Fewer anxiety attacks, fewer triggers, time happily spent with friends and my family. Sometimes I mourn the relationship I originally envisioned I'd have with his family because for a long time, they were really cool. In a way, though, it is good to know how twisted they truly are before marriage so fiancé and I can work on establishing boundaries and making sure we are on the same page. Therapy has been helping me a lot too to set up boundaries that protect myself and my relationship, and to remember I can't control what his family does but he and I can control how we respond..

We wouldn't be having kids for at least 4 years but I set a hard boundary that 1) our family will have no or limited contact with his, and 2) his bad cousins are not allowed into our home EVER. We also agreed that his parents may only visit on occasion and they cannot pop by unannounced like they used to. The last one is mostly because MIL has had a chronic health condition for 10 years now and he doesn't want to regret not spending some time with her.

So now I guess I'm not sure about these things:

• Once other unproblematic family members ask, do we tell them honestly about going LC or NC with certain people?
• Is it right for me to not want these people anywhere near our future family? In my own family, I've seen how much my own grandma aunts and uncles started hurting my mom, their daughter in law. That affected my siblings and I a lot. My parents, siblings and I were okay again after we moved far far away and cut off contact with the extended family for almost 10 years. I don't want a repeat of that now that we know his family's true colors.

EDIT because cousin just now sent a follow-up text saying (in his native language): "I cannot apologize or make amends right now because our family always wants me to be an adult too often and that is bad for my anxiety. I will try to apologize soon." Sigh.

FINAL UPDATE: We're going NC with most of his family at this point. The same day we calmly told cousin it is too late to make amends, and told MIL that she can't keep overstepping her boundaries, my fiancé's grandfather (super awesome person, love him) forgot his inhaler at home when he went hiking with everybody. High altitude made him sick and he had to go to the hospital briefly due to hypoxia. Grandfather did NOT know about this whole groomsman drama, but the MIL convinced people to now blame me for disrupting their peace and somehow influencing Grandfather who lives in a different continent to forget his inhaler. Grandfather is okay now thankfully, and tried telling people they are utterly delusional for jumping to conclusions, which made people think I have "gotten to him" without their knowing. What. Yeah, we're going NC with most of these people!!! Thanks for all your advice on how to set boundaries and be happy without these people, y'all. I appreciate it.