How do I word this? Tellin someone I have mental issue?

How will I tell someOne I have social anxiety? I want to say something like "there's been something I've been meaning to tell you, I should have said sooner but I wasn't sure, I think alot of you and I dont you to think ill if me, but I have social anxiety, that's why I act the way I do, I know how to male conversation, in fact I make it rather well when Im comfortable which is hardly ever, I just feel you should know, it's very hard for me." is something like that ok? People may think I'm shy odd or weird but I don't care about them, I only care about people worth worrying about and I want them to know. I don't like having this. What would you say? Please no jokes. I want it to be explanatory. Thanks.