First of all: sorry for my english, I am not a native speaker.

(I added a “little” background info)
I want to cut my hair but I’m afraid of my parents reaction.
They are not strict (at least not in these kind of things).
The problem is: I have always fought against haircuts (since I can remember) and I don’t know how will they react that I suddenly want to cut it. (I am remebered in the distant family as “the long haired short girl”).
My hair is butt long and have never in my life been shorter (apart from when I was a baby) and I am currently 16 soon 17 (yes, I got tired of it after 16 years)

My parent, grandparents and cousins always teased me about cutting and selling my hair and I would always end up crying (they only teased me but didn’t meant it).

I don’t want to sell it after it’s cut (would be about 40–60 cm chopped off). I would like to keep a strand to put away for years later to remember (no, I don’t find it gross, in my country we are used to this level of sentimentalism). Also, if I do anything with the rest it would be donation (I don’t feel comfortable selling it but I’m fine with giving it to someone).

So, the main point is: I am scared that they will be disappointed if I don’t sell it (and generally their reaction for the whole thing)
It is NOT about wether I should do it or not (because I will either ways) but the best way to let them know about my “plan”.