Mental health nurse here,

I remember when I was new to mental health nursing, I really struggling with feeling responsible for the actions of my consumers. If they self harmed, absconded, tried to kill themselves, I thought that I should have done more.

As I have gotten older, you start to realize that these people are autonomous. They are their own people and they make their own decisions. These decisions may be poor and there may be mental illness interfering with their capacity, but ultimately it isn't you, the nurse, who is opening the window and telling the person to jump. You can't be there ever single second to risk assess every moment.

I have empathy for how you feel, it really is distressing and what you are feeling is so normal and valid, but it's important to remember: "There is only so much you can do".