He’s the scum of the earth like many other men including my husband. He doesn’t deserve nor should he be allowed to see your children anymore.
I’m sure you fear he’ll harm them by “normalizing” things & maybe even getting them involved in porn somehow. That’s what I would think. Those thoughts are valid and not unreasonable.
This world is crazy & a lot of humans (who do they even qualify as human) are sick in the head, especially these types of men. It’s tough to do, your children will push/test you, but have strength and stand up for what’s right. You know what to do and that’s difficult I know it is.
There will be rebelliousness in your teens and I’m only warning you because it’s not about you. When children lose a parent sometimes they’ll defend them when they’re angry that they don’t get their way about something.
If he is allowed to see them he’ll make it all about how you made him do these things and brainwash them that he’s the Super Hero somehow. It’s crazy-making and tough to deal. Stand firm.
That’s my best advice because even though nobody is perfect you’re still the best role model.