I honestly think that going to parties with one’s ex is a bad idea. Getting drunk and passing out in strangers’ houses is probably something you need to avoid as well. It could be dangerous. I’d completely cut ties wuth him and try to focus on other things. Positive uplifting healthy things. Perhaps new friends or hobbies etc etc Start New Year wuth new resutions: no exes and no drinking and no drama. You can do it! Hang in there