A little taste of my depression

Knowing nothing is ever going to be the same again is one of the hardest parts of living... like each stroke of a paintbrush, you are forever changing the picture, and you cannot erase it. Would if just by me singing one tiny note caused life to change? Like caused my brother to move away and leave me, or caused my beloved pet Mia to die? It's scary how such a small thing can make a big difference.
I don't know what to do anymore, my friends are abandoning me... and the only comfort I find now is in music and my friends who are older than me.