I'm so sorry you weren't invited. That was really bad that he wouldn't change his mind, but it is his loss. Maybe you could find a place they are having a big celebration at a restuarant or bar and go by yourself. You might meet someone new and it would be good to get out.

I stay home and just go to bed as usual. I don't find it's something I need to celebrate. Maybe you could rent your favorite movie, pop some popcorn and celebrate with yourself, after all you are what matters. I enjoy quiet times alone. Try not to focus on being left out.