I just came to this thread, Mamid. The only thing I can suggest to you is to spend as much time as possible away from that home with your children. Leave after you wake up and eat, come back when it's time for bed.
These people are terrorizing your children. When BF was trying to break down the door and screaming at your child to open up or he was going to spank him? That was abuse, whether he laid a finger on him or not.
These are crucial moments for your children. They're not things that are gotten over easily, even if they are temporary. Every day is forever to a child. Please try to remove your children from the house as much as possible until you can get out completely.
And then please do those other children a favor and call CPS. I know that you've had issues with them and are not a fan, but this is exactly the sort of situation they exist to deal with. These children are being mistreated horribly and hoping that some mandated reporter picks up on it is not going to do them any favors. What if they don't?