This is awful. I’m so sorry you are in this situation.
speaking from personal experience, he won’t stop.
People like this have a personality disorder. They will behave badly and then twist the situation to get you to believe you are at fault.
There is absolutely nothing you can do to change him. He won’t change.
If you marry him, that will be seen by him, as permission to continue the behaviour.
My ex husband, to this day, believes it was my fault for finding out. And not his fault for the disgusting life he had going on. Porn was just the tip of the iceberg….
He truly believes it was my fault. A normal person stands no chance against people like this.
If I could turn back time, I would never have married him…
Sounds like you know what you need to do.
I agree with other posters, cancel the wedding and be honest with people about why you are cancelling.
Enjoy the holiday with your kids and don’t feel bad, you and your kids deserve it.
Good luck, better now than five years down the line, when he has stripped you of even more of what is left of your self worth.