I had a similar anxiety toward telling people when I was diagnosed also (especially at work). I talked to my psychologist about it and after discussing the issue I felt much better. Similar to you, I was nervous about what people would think and say. I realized that talking openly with people about it would help because I could educate them about ADHD so they wouldn't have those questions in the back of their mind. It not only allowed me to spread awareness and decrease stigma, but also helped me to be more comfortable and really own that aspect of my life. Talking openly with friends also helped to decrease the anxiety of wondering what they were thinking. If your friends don't support you, then are they really that great of friends? On how to tell them, you could still do it in a quite, private place and just explain that this is something you are struggling with and would like their support in your journey to improving yourself. If they say something that hurts your feelings, explain to them that it did (they may not realize that what they did/said offended you). If they are truly your friends, they should understand and would probably be grateful that you shared this part of your life with them. (Also, they may already know and just say.. oooohhhh that explains it.. just like the response you had when you figured it out.) For me, it helped to use comedy when talking to some people. For instance, when I told me dad, I said.."So, apparently I have ADHD.. who knew?" and laughed, which made him laugh. (Ive always been very energetic and sorts, so the diagnosis made complete sense.) I wish you luck on your journey!