Aunt is cheating on her husband

Okay, so my aunt is cheating on her husband, and she’s making her kids call this side dude dad and telling him that they are his daughters. She has 3 kids. 2 girls and 1 boy, he never asks about the boy, doesn’t acknowledge him at all when she sneaks him over. We’ve tried to tell her multiple times that it’s weird to us, and that she needs to fix the relationship between her and the kids dad before anything happens (him finding out and taking off with the kids) he’s soul provider, he’s the only one that works and can support the kids.

But that’s off the subject, I just find it WEIRD that he only acknowledges the 2 girls, only wants to play with them. He tried to talk her into coming and staying the night this past weekend and she told him she would have to bring the kids and he told her he only had enough room for the 2 girls (he also has partial custody of his two sons)

am I crazy?

& yes I know it’s technically none of my business what she does bc she’s a grown women, but I’m usually not wrong about the vibes I get from people, and he’s got bad vibes and I’m scared for my nieces safety.