how to juggle helping your mom with cancer AND help myself?

I nvr realized there was a "Caregivers" section here....my question is my mom has been diagnosed with colorectal cancer with liver mets....onc said 6 mo to 20 months, i refuse to believe this....its been 4 months and i dont like to count months, but its getting harder and harder to take care of myself during this ordeal. I am losing friends, im losing my focus at work, and im losing my basic "want" on things i used to enjoy. I basically self diagnosed myself with depression. I am very depressed, but i am also rational enough to think of how to get out of it....what do u normally do during days when u see your mom in pain but there is nothing u can do, like how on earth can u block that out? since im no doctor, its not pain that ER is necessary, just the "normal" pains cancer patients have....i see my mom make pain expressions and it breaks my heart....how on earth can i deal with this???