I'm sorry things are so rough right now. I totally believe you, too. Self harm is often more about a release of emotional pain rather than sui. It's like a coping mechanism, even if a harmful one. There are people who self harm who are not suicidal, and there are people who are suicidal who don't self harm. I think it's important that you tell someone how you're feeling though. Therapy would be a good thing. I know you feel like a waste of time but you are not. No therapist worth his or her salt would think of you as a waste of time -- they'd want to help you deal with these feelings.
Hang in there and please tell someone!