It sounds really frustrating to be in a positive momentum with your life but to still have these things holding you back.

The hospital will provide a safe environment where you can explore the feelings you have that lead up to cutting without actually harming yourself. I think it has the potential to be a very therapeutic experience for you.

From your posts here you seem like someone who is in control of their life. You know your options, the risks and are well educated on your behavior. Sometimes it can be very hard to just give up that control for a while. I hope that your therapist can help you make this a very positive experience whatever you decide to do.