It is not silly to be upset over a cat. I wish I could give you some comforting words, but it just sucks. Losing a pet is always hard, they're not just animals, they're part of your family.

You said earlier he was purring a lot, and being snuggly. One of my cats who was 14 when he died (I was 20) said goodbye by cuddling and purring. He'd never been so loving before, and when I was home for Christmas break he wouldn't leave me alone. This was a cat who never really forgave me for being a six year old girl when he was a kitten (I was all about the whole "oooooooohhh cute cuddly kitten. I'm gonna love him and hug him and squeeze him and, and,... Mom, why doesn't Pepper like me?"). My mom found him curled up in her closet a few days after I went to back to school.

He just may be saying goodbye and letting you know it's ok and that he loves you.