Is the value you are generating being recognized? Are you going to get some time off after the mad schedule you are in right now? It's a very serious circumstance if your manager doesn't understand how stress can affect you as a resource and as a person -- remember that you can't fool your body, stressing too much will lead to downtime in the long run -- and you will pay it back with interests.

Have a honest talk with your boss. Try to negotiate the situation and come up with a solution that will work for both sides... in my experience, it's very unlikely that the code quality will do nothing but get worse, in these circumstances.

Good luck!

-- ank