OK, it's fairly obvious she poisoned us.
First, she sends us in the bathroom to get a scissors when she has a knife, something you can point out to her. The goal is to get us out of the kitchen while she messes with the food.
Second, she has the antidote as soon as you start feeling unwell, almost like she planned it, possibly before you were even sucked into the game.
Third, what were the scissors even doing there? Who puts scissors in the bathroom? Was she cutting herself? I doubt it. I think the reason it's in the farthest room is to buy her some time.
Fourth, I have to point out the author made it clear, even if it looked like she was eating, her plate was full. So I'm guessing since we're in a game world, she can play an animation of eating, without actually eating.
I have to ask though... why did she mess with the food? I assume it's some method of keeping us permanently in her world? Dependent on her for survival, maybe?