I'm still leaving room in my Agatha Christie mind for a twist in the tale = she could have been royally set up by someone who really did want to get shot of all four.
Can't say more than that but yes, she's not guilty til the jury says so.
I'm trying to be cognizant that we haven't yet heard her defense. In fact, we have yet to hear the details of the prosecution's evidence. But based on what we know to date, I think it will really take a mystery novel type of twist to get her out of this.
There are just too many coincidences and unlikely events for me to believe in her innocence: the fact that the lunch was contentious; that she was the cook and consumed the meal but was unharmed; that her kids had leftovers but were also unharmed; that she claimed gastric distress but the hospital didn't think she was sick; that she tried to get rid of a dehydrator; that she claims she only used store-bought mushrooms and she bought the sole package where a death-cap somehow found its way into the supply chain; that her husband had previous unexplained illnesses; and so much more.
In a mystery novel, those happenings are red-herrings and the real culprit would be the person you least expect. But of course, this is real life and when you start piling all these circumstances together it becomes extremely hard for me to believe that she just had all this bad luck that had the effect of somehow implicating her in deaths.
For her to be innocent would be a bit like if that old movie trope came true: An innocent bystander inadvertently touches the murder weapon and implicates themselves in a homicide. Like Cary Grant in North by Northwest.