Too right, mate.

As an Australian, why bother importing “y’all” when everyone is already “mate”?

Even without development skills, you can still contribute by helping develop and maintain good documentation for your favourite projects or helping with testing and bug reporting.

I don’t think there’s magic one size fits all answer to this, it really sucks you have to deal with it. Avoid destructive behaviours like drinking until you pass out etc, they won’t help in the long term. Do you have any friends IRL you can call on?