Cat, sweetie, nevermind. I hear some defensiveness so I must sound like I was attacking you. Apologies. My intent was to try to get you to shift your focus off of STBX and his current activities. You are still (quite understandably) in a pretty reactive place with respect to his living arrangements. Your mind needs a problem to grapple with in its state of heightened anxiety and its tendency to go into fixer mode. So, I was trying to give you a problem of your own to grapple with and to fix. I was reaching back to your actions during your M, before the bomb. It can be helpful to recognize when old unhelpful patterns of behavior recur. But there is plenty of time to look at that stuff another time.
Anyway, I don't think it sounds at all boastful to say that you've worked on your own issues. You've grown a ton and are doing great, most certainly. People here have a lot to learn from you.
As for STBX's GF, no doubt she is making some lousy choices and even worse jokes. But if she is a horrible, hateful, irredeemable person, then your STBX must be DOUBLY so. For it is HIS responsibility who sleeps in HIS bed in HIS house, who he introduces to HIS children. These are HIS bad choices. She is the guest, he is the HOST. I'm not sure why you want to put the power in GFs' hands rather than hold STBX fully accountable for HIS OWN CHOICES. Given STBX is not after all irredeemably horrible, may his GF isn't either. Maybe your demonizing her is a kind of combined idealizing/infantalizing of STBX in an effort to protect him or the remaining shreds of your image of him? They are BOTH making lousy choices, but only HE is truly accountable for HIS kids.
This woman has nothing to do with your D. It is your STBX's choice to let her move in. It will really be better for you and your kids if you can reign in your hatred of her, especially if she does wind up being around long term. She did not ruin your M. She did not cause your D. STBX is the one who is accountable for who interacts with his kids and how.