Child visitation changes

Help! My ex is an abusive alcoholic who is actively abusing his girlfriends and drinkig in front of my children while they are there for visitation. This is having a negative impact on my sons, ages 6 and 4. I would like to go back to court to modify his visitation, but am afraid I will lose, and out of revnge for me trying to do that, he will "disappear" with them on his next visitation time. What is my best plan of action?

Don't be afraid to go back to court to protect your children from the influence of any alcoholic, abusive or not. They shouldn't have to be subjected to that. Get in there and ask for supervised visitation and make sure to explain why. Good luck.