You know what has helped me? Giving myself permission to not have to put on a show when I'm socializing. Other people manage to go out and not be the life of the party, yet I used to put SO MUCH pressure on myself to stay 'on' the entire time. It's exhausting. So maybe you can go but be ok with the idea that if anyone tells you that you seem down, say "yeah, I'm feeling ok but just am not in a party mood". I think that most people would understand that.

But yeah, I know what you mean. I get 'peopled-out' more and more these days myself. I'm kinda drained by the end of the week, and need more personal space than I used to. You don't have to stay long - just go make an appearance, be a good friend, and then go home and curl up in your jammies.