Please
 

Cutting has completely screwed my life.
I've hidden it from everyone who needs to know and now they have left me.
My girlfriend says I don't love her since I was keeping things.
I hate this. I screw everything up.
If I cut again my therapist is sending me to a treatment center.
I need to go anyways.

Although cutting can be terrible, you're still here and you still have life left that isn't screwed. Times can get tough, but you have to do what's best for you and what is most effective to keeping you alive and well, even if it's something you need to hide and keep to yourself. In time, hopefully you'll be able to share your secret with those around you.

Sometimes cutting can cause us to keep secrets from the ones we love. Cutting is very personal and it's something that often needs time, trust, and lots of thought before we can share it with the people around us.

Just remember, even if those around you can't understand or are hurt by your secrets, there will always be those that will understand.

Keeping secrets is very hard on a relationship, but it kind of sounds like you were keeping it a secret to protect her. You sound like you love her very much.
Sometimes life gets messed up. We make plans and decisions and then something happens and you can't follow through. That's what life is though, it's not a guarantee. You can make all the plans in the world and something is bound to go wrong. Thing is, you are here, right now, in this moment. If you don't like something, change it!!!
You have that option. It'll take some time and a heck of a lot of hard work, but if you want it, you'll fight.
If your therapist is talking about a treatment facility, why wait until it's really bad to make that step? Why wait until it seems like the end to try and turn things around? Until it is to late. Everyone says it's never to late, but if you do something, if you go to far, if something bad happens then it really could be to late. Don't wait. Take that leap and ask for the help you so rightly need and deserve.

You can make things better. Screwing up is all apart of life. You grow up, and you make mistakes. What makes us special is that we really can fight to turn our lives around. Don't give up.

If you ever need to talk, I'm here . Okay?