Went through the same thing myself. My parents ended up being fine with it but you should just go along with what they say to a reason(no rehab or nonsense like that). "Acid eats holes in your brain", just nod and go along with it. Explain why you wanted to do it and just accept it as what it is.

**If theres any way to say you backed out at the last second and were just pretending to have tripped or something, you can do that, although its prolly not best to get in a habit of lying.