Hi Moniker,
Just seen this thread, thought I would add my support. My Dad has bipolar disorder, diagnosed for quite a while after much heartache and a spell on a psychiatric unit. His symptoms present in a very similar way to your DH's. He can be verbally very aggressive towards my DM during a low and she finds it very difficult to handle. The major things that he has found helpful are as follows:
The right treatment. Getting his medication right has made the world of difference.
A good relationship with an understanding CPN, both for him and my mother.
Adjusting the amount of sleep he gets depending on where he is in a cycle- he needs a lot more sleep during a low.
Exercise. Little and often. This has made an unbelievable difference to his mental health. I suppose anything with a sense of achievement might have the same effect.
I think I'll leave it there for now. If you have any specific questions or want any advice or just a chat, feel free to get in touch. I think it must be very hard to handle him directing his frustration at you, but remember to keep telling yourself that he is frustrated too and will take it out on those closest to him.
You say he has highs and lows, but does he have any periods in the middle? My Dad used to be able to swing between the two in 24hrs, but now his medication is working, he has periods of about a fortnight where he is entirely stable with no symptoms. This is the time in which to discuss any issues arising during highs and lows, never during them. That is the one most painful and fundamental lesson we have learnt thus far.
Anyway, lots of love and luck to you.
SOH