Venting goodbye letter before the actual plan or nah

[excusemybrain]

i do not have a plan, i know a lot about so many methods and im still thinking about what should I do
I lost my grandpa little time ago and kinda stopped thinking about killing my self bc it was horrible to see my family heartbroken and at the time I was taking lithium so suicide wasnt really in my mind but now I don't take those anymore and im so sorry for my family but I can't keep going
soooo I really really wanna leave a letter or something for them but im unsure if I should do it before even deciding anything. I just know it's very selfish for me to do it, I don't want them feeling guilty, they treat me kinda badly sometimes but it has nothing to do with me yk. i wanna say sorry I wanna relieve them but idk what should I do I just wanna go and disappear