I feel guilty for existing
What's causing your guilt?
I think it's arrogant and egotistical to assume that life needs someone like me.
All I can tell you is that no one had any choice in whether they're born or not. You shouldn't feel guilty for something you had no control over.
I just don't think I should exist.
You are being unreasonable. No one had a choice if they were born in the world. This isn't something you need to wrack your brain over.