two steps forward, three steps back (burned)

[TJT]

Good not responding. Bad, ascribing mailicious intent to something neutral.

I'm really impressed that you recognized this burned. I was going to say it in my response but I didn't, and you picked it up anyway. Yes, you definitely have to stop ascribing malicious intent.

Even with my H, my mom keeps saying things like "how can you be so calm about this, he just did XYZ to you!!" and I remind her that yes, he did those things and it's impacted me greatly and he should have been a better person to know how it would impact me, but at the end of the day this is HIS issue, and it's not like he sat in a bunker for a year and planned out all the ways he was going to hurt me. It doesn't make his actions less crappy, but it's the difference between "this is a terrible person" and "this person did some terrible things".

You could call it “impression management” in the sense that she cheated on me and left, but still wants to think she’s a decent person ...

See above. She likely still is a decent person, she just did some things the wrong way, as Ginger has pointed out, and probably does realize that. Doesn't make it better, but it doesn't make her a bad person as a whole and I'm sure you know that better than anyone.

and that I’m fine with everything, blah blah blah polite, look how good I’m being about destroying my M. Well, that’s my anger, I own it. She can do what she wants to do.

More blame shifting. Be angry if you need to be but at least look at what's making you angry with more precision. For example, it's not that she's singlehandedly destroying your M. You've admitted that much. So figure out what it is specifically that you're so angry about so you can reframe it and address that more appropriately and help make it go away over time.