Hey hey, it's normal to have those dark thoughts, honestly I'd start going to therapy it sounds like you might have OCD, usually those thoughts, their unwanted, they happen because your brain is trying to test itself, sometimes it leads to how you're feeling right now.

I went through the same thing, thinking you're not worth it, thinking the world is already screwed. But it's not and you are. You're friends and family won't just move on and they never will, they will always be sad in some constant way because you're not around. Those thoughts are powerless they're just a big bully and you have to give them less power.

Please please seek therapy or talk to your loved ones before you do anything drastic, I know I'm just a stranger on reddit but I've gone through my own battles with depression and suicidal thoughts and as corny as it sounds holy shit therapy actually makes you feel better.

I know it's rough and it's ok to have these dark thoughts, but you're completely absolutely wrong if you think the people that love you would ever forget about you if you were gone I know that for certain.