Can't move on because I know my parents know

I was going through a very hard time mentally when I was 14-15 and did things on the Internet I shouldn't have. My parents likely think I was lying for attention, when I was truly just a mentally ill kid. They've used it as an excuse to monitor what I do since, even though I'm an adult now. I have since done other things they don't approve of, and I'm terrified they'll tell all this to my grandmother i live with, and she won't understand why I did the things I did. I feel so sick from anxiety all the time and I hate myself every day. I just want it all to stop.