I can't add anything to the great advice you've been given here Jeni.
But I do want to agree that public speaking is not a requirement for attending AA as Deeker said, so please please do not let this stop you from going to your meetings.
Just take that coin and say Thank You...you can even say "I'm speechless".
As Billy said, maybe work on it by taking small steps and not putting so much pressure on yourself.
I hope your sponsor learns to be a little more understanding.
Love Venus xx