My girlfriend has severe depression and I want to quit the relationship

I created a new account for obvious reasons.

Dear redditors, I have to deal with a very hard situation and I don't know what to do. My girlfriend has severe depression for a few months now. She is getting intense treatment but she still has very serious suicidal thoughts and I had to bring her to the hospital the second time today because she was about to get serious.

I was questioning the relationship for a long time already for several reasons and the depression of cause did not help. Now two weeks ago I decided that I can not see a future with her and I want to end the relationship.

The issue I am having now is of course that I am affraid breaking up with her will make her thoughts become reality. She told me she is so affraid of me leaving and losing her last safe pillar in life so I always told her I will stay. I can't tell her the truth but every day with her destroys me more and more. I just can't take the responsibility anymore. I have the wish to run away but I feel like killing her by doing so.

Has anyone dealt with this already? What should I do?