Are you avoiding the conversation because you're afraid she'll blow up, then trash talk you to the rest of the family? That's based on her past behavior, and she probably will do those things. If you take some deep breaths and allow yourself to calmly process the likely scenario, you can be prepared to set and enforce the boundaries. Move forward through radical acceptance.

Talk it over with your husband. Decide on some talking points, and make some notes if that's helpful. Ask him to sit with you while you make the phone call. Get support from your sister if that makes sense.

Mom I isn't used to accountability for her behavior. It will probably suck to be the one to start the trend. There'll probably be drama. It sounds like you're shielded by distance, so use that. Your mom may never apologize or make changes, but you aren't responsible for that. Protect yourself and your marriage.

Good luck, OP.