Then it seems you have answered your own question. You would treat others with understanding. And I think most people would do the same for you.
If you feel that it helps you with your anxiety now by telling people this when you are giving a presentation, then I think that's perfectly fine to tell them.
Good luck with any presentations you might have! Remember that you will get through it. You will survive. You will be the same good person after the presentation that you are right now.
On a side note, I went to a Toastmasters meeting last Monday evening. They were a nice group of people. There were 4 new guests coming to their meeting for the first time, including myself. As usual, the guests were asked to introduce themselves at the beginning of the meeting. Just a short "hello" stand up sit down introduction to the room. One of the other guests was was a woman who told us that she had always been extremely scared of any presentation all her life. She said she had no problem speaking to friends, to groups, even to us right then as she was seated in the room, but the moment she is to get up and give a more formal talk, it all turns into this big thing she hates. She did not seem like a socially anxious person at all, but as you know that is not easy to tell if someone is or not always, unless they say that. She did not say that. She easily talked and mingled with the group later and was very open about her feelings of just being frightened of public speaking, which is a very common fear. So, she did tell us, the whole group, that she was scared of speaking. My feelings at that moment when she told us that was understanding. Nothing negative. Many of us spoke to her during the mingling break in the middle of the meeting. I was speaking with her in a nice way while the president of the club was speaking to her and being supportive. She spoke to plenty of other members also and I saw nothing but friendly, happy people talking to her. Each person reacted in the way that you say you would react, too.