She wants it to be noticed, lets make it noticed.
Relevant Topics:
Her admitting to the crime: I stabbed my husband in a delusional episode
Her husband wanting it forgotten: it is what it is
Her begging me to help: Turncoat
Bottom Line: She's been spamming someone she wants to poison, then she stabs her husband thinking it's his father within a short window of time. After a history of self-harming behaviors as well it's clear that it's spreading towards those around her, qualifying as both "A Danger To Herself and Others".
He clearly wishes to bury it, like he's done with every other time she's acted out, but he clearly does not see what risk that's putting both them and other people that there is in doing so. You two should seriously consider getting her checked inpatient somewhere, before it's done involuntarily and therefor a worse outcome overall. You two can't fix this yourselves, it will get worse, GET HELP.
If you keep asking me for help, I will call them for you.