Am i ok?

People often ask me if i'm ok. I always say that i'm fine. You wanna know why? Not Because i don't trust them or because i don't want to open up to them. No, because when i say that i'm not fine they are gonna ask why. And i cant explain why i feel like this. I cant explain why i lay awake everynight, overthinking. I cant explain why i burn myself everytime that i dont feel like living, No. I cant explain why i'm sad or not fine. And yes ofcourse i would love to open up to someone but I can't. Because they won't understand.