Fluffy, your desperation and despair is so clear in your posts it is hard to read and hard to imagine the pain you are feeling. I'm so sorry you find yourself in this situation.
I know I have said this before and you may not believe it but you deserve happiness and a meaningful life. You have survived so much already, I truly believe you have an awful lot to offer this world. It's clear from the support you offer others. Many NHS trusts are desperate for experts by experience to work alongside professionals to help others. From the advice you give and your compassionate tone I can imagine you being invaluable in such a role.
In these darkest moments please try to hold on to the people who love you and who you love. Please think of the beautiful things in this world, and the things no matter how small that give you pleasure. There is life out there that is worth living. I know from your thread you have hopes and ambitions, you deserve a shot at them.
This may be unpleasant to hear and please tell me so but the unit you are on are not going to let you kill yourself. They are going to keep you safe. If this means constant observations and PICU and a section 3 then that is what they will do. Please consider though that these methods may harm your long term recovery. Please fluffy dig deep, like you have before and fight this. You can start to take responsibility and move towards recovery. You can start to think about things that can help. There are so many more beneficial and kinder treatments than the ones available to you right now but ultimately you have to chose that is what you want.
I am thinking of you tonight and hoping you have a restful night and a more positive day tomorrow.