I hope things worked out. I was taking 100mg per night and I had similar problems.... no memory of anything that took place. I went through hell because I quit cold turkey with no medical supervision. I almost died. I did not sleep for 26 days. However, unlike your husband, I was taking this amount for 1.5 years. Good luck.
The maximum dose is 70 mgs over 7 days and he has taken 400. This might require a detoxing because the withdrawls as said by other replyers is a serious situation. There could also be numerous nights ahead where getting sleep of any decent length will be nearly impossible as you go through the tapering process. Our own brain's chemistry gets seriously disrupted when artificial substances are taken. It takes a period of time for the brain to kick in again with its own sleep producing chemicals after being flooded with too much artificial chemicals.
Yes, wean off of the pills, cold turkey can cause a lot of other problems. There are a lot of good calming teas that help with sleep/stress issues. I like the sleepytime tea and tension tamer from your grocery store. Might help with any withdrawals or side effects from the drug.
No! He should taper it down. Get the pills away from him. Take charge of them and dole them out.
Get a doctor involved for a taper plan and do it fast!