Thank you for posting.
Welcome to MS.
I think other guys have well explained what sexual abuse means. I would only say that sexual abuse can take forms of eposure of intimate parts to another person who did not say they agree to see it, or if the person is very young to be considered an adult.
While it is very good to find an older friend who takes care of you, be careful about what he says and does, as roadrunner told you. He is just an adult man who may help.
When you feel all alone and unhappy, turn to you Inner Child and talk to Him.
You will see He can comfort you like nothing else!