I just can't wrap my head around that he won't be around anymore

My nephew killed himself last weekend, we just had the funeral today. I've had plenty of other funerals, and they all hurt but nothing like this. He was just so young and seemingly full of life. It literally just doesn't feel real, i just can't believe that I'm never going to see my nephew again. I just wish I had been a better/more active uncle in his life.