And step parents are often the architects of their own suffering by not knowing what their role is/isn't and staying in their own lane.

It's not always easy for people to see that their biggest obstacle is: THEMSELVES.

So many times I see on here "if he/she/it would change". And that is the problem. YOU want that change, but no one else cares. I just wrote on another post that your partner may make half-hearted attempts, but then goes right back to the same ol'-same ol'. Because they do NOT want to change. 

To me, it's like losing weight or quitting drinking pop or quitting smoking: that person has to WANT that change and be ready to change. For some of us, it's seeing that WE are the problem so we need to change our behavior, our expectations, or ourselves. Or move on.

It's rarely one person or thing that is the problem. It's usually a combination of multiple people/things.

For me, I know BM is the cause of many problems in general. BUT, how my DH reacts to her shenanigans (mixed with his own parenting style) plays a big part in our marital problems. Plus, I like things a certain way, and there are just certain things I'm not willing to try or do (to my own detriment) unless it's absolutely necessary because it's anathema to who I am.

It's hard to blame the people we love the most, and even harder to shine that light on ourselves. It's absolutely crucial, though.

My problem is that i "go off" whenever something comes up with the ex and then i look for more evidence. My SO accidentally called me by her name last night when he was telling a story to his parents. I wanted to let it go but when he asked what was wrong, i couldn't help it. He also told me that he would stop letting her interfere with "his" weeks. She has either picked up the kids for an hour each day or texted him about it and it is his time. And after i made him promise that, today, since he has the kids and is off work they would leave each other alone (he wouldn't respond to her) he "had" to text her today to tell her to be careful about the coronavirus when she gets them next. Each time i yell and nag. Tomorrow her week starts and their status quo is daily exchanges. I have to stop nagging. At this point i need to find another tactic, but i just can't seem to shut my mouth and think. Nagging doesn't work. He knows i will just keep bitching and keep taking it. But what else can i do?