If the cops called you with disturbing facts about the accident, could you possibly get a police report to back you up for breaking the order. If I were you, I'd get that order modified to benefit those kids and you asap! Go for supervised visits n have his overnights terminated immediately. And if you can mandate him to undergo a court ordered alcohol test (You may have to pay this yourself) it could help you emensly in having the kids 24/7. When people fighting addiction are forced to set up supervised visits, they become overwhelmed n the kids don't seem worth the hassle it takes to follow through with all that work to see them n they actually take time away from the drinking/drug use.
I went through this with my granddaughter n her heroin addicted father. I took a 50% custody order off him and destroyed it with court ordered hair follicle drug testing that I paid for. He ended up calling my daughter in July n telling her that h e was done witb my 5 year old granddaughter because she was in the way of his lifestyle. She was upset because she needed help with school clothes. I told her, I'll buy them and wave goodbye to the turd! He did the best thing for her by walking away.