Yesterday we woke up and he was gone

Yesterday I was woken by my older sister at 7 23 a.m, she was sobbing and only said 3 words for me to run out of bed. "Simba isn't moving" the thing is, he was our youngest cat, not even 3 years old. He had been fine even the day before. We woke up and...he was gone. At around noon we buried him at our grandparents. I know its only been a day so its normal, but I just don't know what to feel. Sometimes I'm sad or angry or numb. Idk. Just...need advice