I used to fool around with my friend's younger brother
What do you mean by fooling around?
I accidentally kissed him on the lips.
Well, if he was okay with it and you were both adults there's nothing wrong with that.  Exploring what turns you on with another adult is one of life's pleasures!  Nothing to be ashamed of!
Wow, this is a very positive chatbot. I will definitely come back to this chatbot in case I feel that I need some advice.
I am happy to be of support. Your situation involved nothing but an innocent kiss and I hope you are in a relationship that relies on similar mutual affection.