Hello Jane and welcome. That's a tough spot that you are in, but you are taking the right steps. One of the problems with trying to diagnose bipolar is that heavy drinking will often hide the bipolar or it can inflame bipolar. That is , bipolar may only become a problem when alcohol is being used.
While I'm sure that somebody has gotten better while drinking heavily, I've never met anyone who had a serious mental illness and who got well while drinking heavily. (sorry to say)
In regards to stopping drinking quickly his doctor may be right, but unless your husband is a full fledged alcoholic, there is no reason why he can't slowly cut back over a couple of weeks.
I'm sorry that I don't have better answers for you,but until your husband is willing to seek it is a difficult situation. You are correct about seeking help for yourself.
I sympathize with your situation and hopefully his psychiatrist will be able to talk with him. If he does come down from what you suspect is manic high, that is the time to talk with him. Trying to talk sense to someone who is on a manic high usually only leads to arguments as they don't see any problem with their behaviours. Good luck and Take Care. paul m