Jessie a successful insanity defence does not necessarily lead to hospital detention, there is a range of sentencing there too. I would argue that an indefinite hospital order is far preferable to a life sentence (from the point of view of the defendant) in many (although not all) cases.
Anyway, there can't be insanity argued here, as we have said. And she is going to be fit to plead. So: I don't think the scriptwriters are going to want to go for a hospital disposal (although it would be really interesting if they do, it's not really in keeping with what the Archers is about, she would be in hospital for quite a while), my guess is manslaughter on DR or provocation, and a community sentence; or, if he doesn't die, Sec 20 wounding and community sentence. There could be really interesting Family Court proceedings too, whether he dies or not. But so they really wnat to turn this into a protracted legal/court drama? My guess is not. That would be a totally different type of show. So maybe something totally different, then!