I'm sorry for your loss.
I do believe I do have an answer for you.
I am a man of science, however I do have faith too.
I've found that the best way to put it,
that satisfies all criteria & thought.
Is that after death, you are in another "state".
Nothing is lost, just in a different context.
Conservation of Energy, if you would prefer.
Simple, yet profound
Just like the best ideas,
in science or philosophy.
It's just our current viewpoints & knowledge base have not "defined" everything as yet.
This is true, no matter what you believe.