Yeah, the things I know about my mom involve abuse she went through in her first marriage. Telling me was so inappropriate, because for one, none of my business unless she wants to tell me. And second, he's my siblings father, and I interact with him at least once a year. It just put me in a weird space to be keeping a secret I shouldn't know from my siblings, and keeping a secret from my mom that I know at all. (for what it's worth, it appears he's a very very different person now. If he was still awful, my mother never would have swept it under the rug)

The way our extended family dynamic works right now is the way my mom wants it. She went above and beyond to go the opposite route of perental alienation by never letting my siblings know how awful he was to her, so we could all come together peacefully for gatherings/events/holidays. She never would have wanted to put me in a spot like this other family member did.