Have no contact with them. Absolutely none. If there are children involved, have as minimal contact as possible. Keep your conversations civil but brief. The only was to deal with abuse is to remove yourself from the abuse. Also, if there are children involved, please take every precaution to protect them from the abuse. Generally speaking, you were able to make this person an "ex." The children do not have this luxury.
Take care of yourself and refuse from this moment on to be treated badly. You deserve better.