Who knows what’s her agenda. Or maybe she has none. How well do you know her? If not at all, then you have no ways of knowing and it’s not important what she does and why.

I understand him wanting to play nice but I think I’d want him to play nice with me, not the ex. He doesn’t sound like a timid shy guy who can’t say no. Keeping you happy and not going mad should be more important than keeping ex nice or protecting stuff he stores there (why is he storing stuff in ex house while married to you, why not get a storage after all this time?). If he is annoyed and angered by ex contacting him, he needs to block her.

Hopefully all of this ends immediately. Put your foot down. He might not grasp how much it upsets you. Well maybe it needs to anger you, not upset you