I’m so very sorry this happened.
Let Chao-Guay have her with him for an hour. I think in some sense that they do know. Rabbits and other animals can groom a toy even though they know it’s not live. He will need you a lot more now for some time now. You probably don’t want to think about getting another pet now, but sometimes it’s the best thing for a bereived rabbit, to be rebonded soon.
Choking happens sometimes with rabbits. It can’t be 100% prevented. You can lower the risk some by scattering the pellets on the cage floor to slow eating down. There is a bunny Heimlich manoeuvre, very different from a human Heimlich, that you can perform if a bunny chokes on something. We have had members use it successfully in a few instances: http://rabbit.org/the-heimlich-maneuver/ In your case this would probably not have made a difference seeing that the food particle she choked on dislodged of it’s own.
Again, I’m very sorry this happened. It is horrible to lose a rabbit.