I'm kinda living a big lie to my parents
What kind of lie is it?
I'll tell you one thing it doesn't relate to sex.
It is hard not sharing with the people you care about but it is normal to want to keep somethings to yourself. They should be able to understand that.
I really hope that is true.
Not everything personal needs to be shared with everyone. Even if they are your parents. As long as you aren't hurting anyone and you don't feel its urgent or struggling with the truth then you shouldn't worry about what you haven't told them.