Joe, I'm not going to tell you to not feel the way you feel. You're feeling that way because of how great of a person you are.
I can say that there's little as difficult as doing everything you can to help someone and still see them self destruct. It feels like there was just SOMETHING more, that if we had done it, would have saved them. But there isn't. There wasn't. A person will only accept the help they're ready to accept. I'm so sorry that his not being ready resulted in his death and his future child never knowing their father. That guilt your feeling is a constant reminder to keep trying. Because once you stop, once you give up on people, the world loses something special. It's a hell of a struggle to try to help people and only succeed some of the time. Those times they can't be helped is like a dagger in our hearts.
I'm so sorry man. I really am.
Also never kick a damn cat. But feel free to kick whatever cat is backwards.