My 2p worth? As someone who has been where you are to some extent - we went through 2 breakdowns and it is something we live with - even today Marc has had a big wobble so my role today wasn't "wife/lover" it was as supporter/carer/cheerleader/person to provide food and drink..... Today he isn't able to make decisions, his brain is "mush"(his words not mine) and today anxiety and depression have grabbed hold....
This may never completely go away for us - and it is US. We go through it as much as we can together. We've had good days and more frequent great days, today isn't one of those and I know there'll be some more crap ones in the future. Do I believe we can stay together through them? Yup...
Can you say that you can do this time and time again? You may have to....