Why is suicide a sin?

I’m depressed and anxious, been depressed for most of my entire life. I literally suffer every day. I pray and reach to Heaven for help but there’s no answer.

(I always get the “Well you need to work harder, because if God isn’t answering you, it’s your fault.” So spare me as well as the false “I care for you” as well as the “suicide is a permanent solution to a temporary problem” cliche).

No one cares if I’m alive or dead so why can’t I die and go to the world to come? I’d end up in Hell but if God wants me to suffer every day and isn’t giving me the grace to bear it, why can’t I just call it quits?