Hello, welcome to the FRA, the free-rant area

You are right, it is unforgivable
I may be biased, becaused I still have to fight to keep pa and ma at bay, at my age. And I not always succeed, GRRR

You may consider forgiving only if they realize the error and apologize warmly.
For the future, write secrets in a file and encrypt it.

Having said this, you shouldn't even do something just because your parents don't want you to. It would be just another way of being driven by them!

For instance, as an autonomous individual, you may want to quit smoking. At your age it can make a LOT of damage.