What is the best way to cope with a pet who died suddenly?

I have 6 and 1/2 year old cat,Lucky, who died last friday morning while I was away for work. My mother informed me on Saturday that my pet is gone. She saw her under the table dead. She said that my cat looked perfectly normal on Thursday, but did not eat her supper and slept under the table. When she wake up to check on her, she was shocked to see that Lucky was gone. She had her buried at the back of our house. I am so devastated, I can't concentrate on my work. I keep on thinking that it was a good death- she did not suffer. But I feel terrible for not being able to say goodbye. Cat owners out there, help! Thank you!