The part that makes me mad is she brought her new boyfriend into my house to get the things knowing I don’t want him here.
It’s not unreasonable at all.
It’s simply wanting the fundamental value of respect.
The problem is, your STBXW, like my XWW and almost all who commit this betrayal, don’t live by virtue of values, moral code, or principles.
They live by virtue of what other people think of them.
Everything they do, how they act, how they dress, and how they treat other people is based on how they feel other people view and think of them.
It’s the "seeking external validation" that drives their behavior.
Your STBXW knows she betrayed you so she also knows your view and opinion of her is, as would be expected, very low.
Therefore, she has no motivation to treat you with any semblance of respect because she doesn’t expect any praise, or validation, from extending any respect to you.
Her being respectful to you doesn’t get a dopamine hit of a "You’re pretty!" or "You’re sexy!" in return.
In fact, it’s the opposite in her view as you, involuntarily, will always be a living reminder of what a total failure of a human being she is.
Going back to that house and seeing your children is also a reminder, so she needs to bring the new-guy-source-of-value with her to feel better.
Just always remember that none of this shit she has done has anything to do with you.
He already has my ex wife…
Listen, please don’t view this as though her adultery guy has won some kind of prize in ending up with her.
I can assure you - he has not.
People like this are not a prize - they are parasites that need to feed off others emotionally and financially.
In time, you will be breathing easier and feeling better not having this emotional black-hole treating you like you the troll under the bridge in her Jerry Springer fantasy world.