I can really relate to this - I had very similar worries when I went to my first social with my old partying crowd.
First, am gonna link to some threads with some helpful advice on how to handle boozy situations sober, would recommend spending some time reading through them!
For me, going with a non-alcoholic friend, planning my drinks, having a plan to leave early and a reason to get up early the next morning were all key. Something I found interesting was how many people left before me and how many people actually drank a lot less than I used to. There were a few people there really getting on it but that started later, and I was getting tired by then. It was weird not be part of the last one standing crew but I had such a good evening. I was able to connect with people I hadn’t seen for ages and I could remember it all when I woke up fresh and hangover free!
I imagine there will be others who will carry on partying into the night. Honestly if your friend is a blackout drinker they probably won’t remember when you leave! When you were getting wasted did you notice all the people that weren’t there? Or were you more interested in keeping your buzz going? If you’re worried about it you could always give them a heads up that you’ll probably get going early, but offer to celebrate with them another time another way e.g. brunch, cinema, something active, something pampering… Whatever your vibe is.