I wrote a letter to my mom explaining that my feelings and dysphoria haven't gone away, and they've just been getting worse. I explained that I love her and would willingly give myself up for her, seeing as my grandmother wouldn't be pleased and nobody knows it wants to know what she would do if she found out. I would try to fight first if she reacted poorly.
I made a metaphor for it as well.
I compared myself to a puzzle with a few wrong pieces, and the puzzle maker (the one putting it together) is trying to mash the wrong pieces into place which is ruining some of the right pieces. The missing pieces, which have been replaced by the wrong ones, are in a locked box, and my mother has the key. Only a few are in this box though. These pieces represent my pronouns, name, and possibly getting a binder/packer, and being seen as male. That kind of thing.
The final pieces, which are in a more hidden box, have more locks. The locks are paperwork, money, time, age, etc. Those pieces represent surgery and hormone therapy. The keys are harder to be found. Sometimes they'll get lost and we'll have to find them again. But we will.
I didn't have this much in my letter, but I'll explain more to her eventually.
Au revoir!