I understand. I had my father's lunch box which he took to work every day. Just a tupperware box. but my dad died when I was 12, and I used the box for various things when I left home, each time I used it I thought of him. I don't have many photos of him (3, in fact) because my mother has the photo albums and isn't sharing. So when my then-husband put dad's box on the cooker and turned it on, I was inconsolable. his response to melting dad's box, something he knew was irreplaceable, was "huh. It's just an old box. Get over it" and acting hurt that I was upset and angry at him.
So yes, I understand. And I'm sorry about your knife