it would not be a failure to seek respite from this behaviour assuming it linked to his "illness".
you have DC to think of here.
does he stay with you 24/7? do you and DC get to go away stay with family /friends without him?
does his diagnosis come with a recovery time scale? does his diagnosis coem with agressive behaviour? if so which meds would cut that out? what strategies/behavioural approaches are they working with you on?
you say he saves agression for you -then he does have some control.
my ex had depression got aggressive/violent etc, does have MH issues and yes it was hard sorting out what was MH what was abusive behaviour - but fact is if someone is agressive/angry etc towards you (for whatever reason) then it isnt right that you put up with it. you don't have to live with that.
where is the medical evidence that doing this to you and taking it out on you helps his recovery?
at what cost? your own mental health?
in sickness and in health does not require you to suffer from his ill health, not to this degree - nor your DC. how old are they?
you would not treat a cancer yourself or a broken leg - you dont have to become his "treatment" day in day out. seek help/respite care.
if you can get regular respite from him (you have become his carer after alll) eg he goes away to stay with friends/family or hospital - or you get to go away from him - then fine chose to stick with him....but if you cant build in respite from this awful behaviour then you becoming a martyr.
if you take it he is ill - well fine but no one should have to live with that kind of behaviour day in day out. you will suffer so will your DC. ask for meds to control this behaviour calm him down. espec if there is no time scale for recovery...
my exP's GP has written letters saying being with his DC etc could "help his recovery" - well cr&p to that - the DC are not there to treat him, when he has treated them badly (long story) .
you have to put you and DC first in this - if it really is part of his illness you must consider seeking respite away from him and real help with caring for him...if he can actually function on his own get dressed make his dinner etc - then leave him alone for a weekend and see how you feel.
you've given six months to being with him - no recovery.
what realistic prospects another six months will make much difference?
what if you live apart and only see him on good days?
what incentive might that be to his recovery? what meds could calm him?
maybe he will never get better - what about a few years down the line? how will you look back?
start getting breaks from him away from these moods for your own sake. every carer needs respite ...
maybe try using written instructions/visual reminders as to how to behave ?