Masteriusz, I'm certain your brother continues to exist and that he's very sorry for the pain he caused his family and others who loved him. No matter how intelligent or gifted a person is, they can be very lost and make very poor choices. It's not your fault. There were many things going on in his life that you knew nothing about, how could you have correctly evaluated the situation? Without a precedence, how could you have known the signs? Even if you did, how can you know that this was something he didn't do somewhat spontaneously, thus, with little warning?

Because you have learnt so much from the experience, it's possibly karmic: something you came here to experience as a human being.

I'm sorry for your pain. You're very welcome on these forums.