Cats fighting...please help!!?

So it's 2:30 a.m. My pregnant wife and I haven't slept all night. She has to go to work at 4. I have to go to work at 6. We have two cats. They're brothers and 6 1/2 years old. One is a bit territorial and the other one has always been pretty docile. They've fought in the past, but never for long. They get along pretty well. Today has been really strange. So lately, I've noticed the docile one has been vomiting a lot after eating. I think it's because the other one has been territorial about the food and the docile one has been eating too fast. I've tried to help with that by giving the other one some cat nip in another area while the docile one eats. That seems to be helping. However, today's presented a different issue. The docile one has been terrorizing the bully...non stop. It's to the point where the bully seems to be afraid of the docile one. Every time the docile one enters the room the bully is in,the bully starts growling and hissing without break. This has been occuring all through the day (at least since my wife got home) and every half hour throughout the night. The docile one doesn't seem to be instigating anything at this point, sometimes doesn't even look at the bully, but as soon as the bully tries to leave or run out of the room, the docile one bolts after him and attacks him pretty fiercely. It sounds like the other one's screaming at him. I've tried keeping them apart, but it's tricky when they share a litter box. I have never ever had this issue before. Nothing seems to be wrong with the docile one. Other than this, he's been acting totally normal and hasn't been aggressive in any other way. Has he just had enough? At which point, how do I stop this? If anyone can help me, they'd be my hero. My wife's expecting any day, and I really can't be dealing with this on top of a new born. PLEASE HELP!!! Thanks.