Hi Katy
Please don't beat yourself up over this. It needs looking in to but isn't the end of the world. You can talk to us anytime you need to. I wonder if there's a clinic or something near you, so you can talk to somebody w/o your mom knowing. I've been in your shoes with the cutting;the difference was I never felt bad because of it. Others made me feel like a total loser if they found out but I hid it well.
I really hope you can hook up with some caring people once school starts. In the meantime, we're here!