Hey
niamhh, I'm new here too. I have actually cut before too; it was a few years ago. It was never deep cutting and it didn't last a crazy long time, but I did get scars. I'm sorry you're feeling so bad, and all we can do is offer our support.
Not even my friends knew about my cutting. The only reason I stopped is because my mom saw my scars one day. It hurt like hell for my mom to see me in that state of mind, but it opened my eyes to those who actually
do pay attention. Like we are to you.

You said your friend knows; how is she handling it? What is her opinion? Is she a source of comfort for you? Those things might be important. Having someone to lean on is key. A doctor or T can help, but only so much. Not sure if you feel comfortable enough to go to your friend, but seeking help can only do that -- help!
Like I said, we're all here to support you.