What's the hardest thing you've ever done?

Telling my dying mother that it was OK for her to go. 

She'd fought long and hard against her cancer, but it was clear she was tired and that her time had come. I wanted to make it easier for her, and was told by the doctors that hearing is the last thing to go.
So I told her it was OK, we loved, we were proud of her struggle and it was OK with us if she wanted to slip away.
I've teared up just typing this.