I am so sorry for what you are going through.
I think the #1 thing you should be thinking about is your children. I know you love your bf, but you love your children more. If he continues this way, it can very well get back to your ex-husband and you could lose the rights to have your children as much as you do. They will grow up wondering why you let it happen. My mother always chose her bfs over me and I will always remember that.
Take care of yourself and your children. Get out while you can, before things get worse. Because they will.
Many ((hugs)) to you.