How are you going to handle your children's problems because you stayed? As for supporting his children financially, he needs to get a job! If you leave, you should go to court and get child support. This isn't your decision; your children have a legal right to financial support from both parents. One parent can't say, "I don't want his/her money"; by law, your child has the right to it.

I really think you need to talk to a therapist to help you find the strength to do what you need to do.