Listen to me to the end! What you did was wrong, but you weren't wrong. You did all you could to fight your fate and took the only path you saw ahead of you. That is something to be admired. I made someone lose an eye for no other reason than that I was angry and scared, in a way, that is a lot worse.
You fought with all you had to grasp that last possibility to happiness. If I thought killing someone would save you, I would have done it in 1500 seconds! I wouldn't even give you the chance to do it yourself if I knew. And I'm proud I can say that I would do something like that for my friends.
But... as I am now... I now I could slip and fall into that darkness in a single step, I could lose my mind again and just hurt... everyone around me again. But! As I am now, I want to believe there are other choices. The only path you could see was killing that person, and for that reason taking fate in your own hands was the "correct" choice. But if you had talked with those around you, if you had discussed it with Narumi and others beforehand, maybe another path would have appeared. One that didn't even exist before.