Hey Robert,
I know that social anxiety can be really hard, but going to one of these games on your own is one step forward to overcoming it! You're in a situation where you're forced to converse, and while that might not feel like the best thing, it can show you that you can socialise and that it's not always as scary as it might seem! I'd probably just advise you to try to stay calm and take deep breaths.
And I agree with Cassidy. All of this has nothing with your brothers. If they want to judge you, let them! They don't know how hard social anxiety can be and have no right to make you feel bad about what you're experiencing.
Hope this helped somewhat and feel free to
PM me if you ever need to talk!
Kyra