Rant and vent away! This thread is so cathartic and reassuring that others understand exactly what you’re dealing with and that, just because they’re your elderly parents, doesn’t make them sweet old dears.
Oh goodness, it sounds as though your poor FIL definitely needs protecting from her, and thank goodness hospital safeguarding are onside and aware!
Am I reading it correctly that your MIL is now permanently in a care home too? If so, try and reassure your FIL that she is perfectly safe and being looked after, so he doesn’t need to be anxious and jump to all her demands. These personalities are very skilled at convincing those around them that they are helpless victims, when ironically it’s those around them that are the most vulnerable to their manipulation.
If your FIL is still worrying, is it also worth ‘selling’ it to him that for the next few weeks he needs to focus on getting himself well again, otherwise he won’t be able to look after her? Hopefully then, after a few weeks, you will all be able to break the cycle of her controlling him, guilt tripping him and alternative arrangements can be made for his long term recuperation.
My mother kicked off majorly when we first got her into a care home - I initially told her it was just for respite care - and she would never admit it to me, but she eventually loved it; all the attention, a captive audience who would listen to all her opinions and moans, being waited on and (in her mind) everything revolving around her wants and needs.
As has been mentioned on here, we’re all socially programmed to feel responsible for and have a duty of care to our elderly parents but these personalities aren’t your ‘usual’ senior individual, they have a lifetime of manipulative and bad behaviour which their old age seems to bring into sharper focus and gives them an even bigger excuse to exploit those around them.