Pre therapy I read a lot of self help books. I bought how to win friends and influence people and surprising it helped me learn how to talk to people. When my anxiety was at it's worst at around 16, even talking on the phone was hard for me. The authour Dale Carnegie also wrote one specifically about public speaking which I have. a quick google brought up the title : How to Develop Self-Confidence & Influence People by Public Speaking.

Also perhaps you can start small? Could you give the presentation to a few family members first so you could practice with an audience?