Hey, feel your pain...
Over the last 15 years I have lost 2 very close friends to suicide. One was completely unexpected, and I felt terrible that I couldn't have helped him out...just had no idea. I was upset that he didn't talk to anyone about anything like that, as he certainly had friends that cared about him. Just a big ' ? '
The other was not as much of a surprise. I saw the decline, and I tried to help. Just didn't matter. The mind seemed already made up.
I also recently lost one of my long time buddies to an auto wreck. Just motoring along and some dude swerves into his lane head-on and kills him. He had so many friends that there were 3 funeral services in 3 different states. I miss my bro, RIP Keith.
Personally, I don't really get over these things, I just learn to live with them and learn something if possible.
Sorry for your loss...but you are most certainly not alone.