you're not stupid.... they are inconsiderate.
happy birthday and congratulations on your sobriety!!!!
I know this must really hurt. There's probably something in this experience for you to see, learn, grow. Often our more painful experiences are our more insightful.
That doesn't make it easier, but it can make it productive.
Stick to the sober path and next time, choose a different group of people. Or maybe even just one person. Start there... build anew.