I'm gonna tell my friend that I hate them.
Why would you do something so cruel? Do you actually hate them?
Yes. I can't stand them anymore.
If you just want to see the person less, then you may not need to tell the person you hate them. Just be up front about it and honest without being so hateful.
I can't help myself. I need to say it.
Telling them you hate them won't do anything good for anyone. If you want to end the friendship, simply tell your friend that you want the friendship to end. That way you can both go your separate ways without either of you feeling overly angry.