I'm not able to let it go
I am sorry to hear that. What is it you are trying to let go?
It just keeps me a nasty mess inside my head.
You can't help if you're feeling like this. Get professional help so you can move on and get back to your life.
Maybe I ought to cut my wrists, I just can't deal with this feeling.
You have been holding onto anger and it is making you think bad things. Usually people seek help for these types of things.