I can't see what's the problem, nor the cause that's making you to do this kind of stuff, but you must stop, before it gets any worse.
I recommend you to tell what's happening to your parents, before they find out by themselves - and seek for professional help of a psychologist, instead of informing us about this here, on Newgrounds, where as long this could sound cruel, there isn't any other solution we can offer you than going to therapy.
DeaghlanNG
Here's what you do, it's very simple. Put the knife down and do literally anything else besides cutting yourself. It achieves nothing.