Nothing you really can do. Losing a close friend is painful and it puts you in a situation where you don't know what to do with yourself. It is alright to grieve. It sounds like he/she was taken away too young and it wasn't of natural causes. Just try to be there for the family and just try to surround yourself with positive vibes. It gets easier as time goes on. But just try to think of the good times you guys had together. And just know he/she is always gonna be with you. Sorry to hear about your lost. Just try to keep your head up.