Sorry to hear about that. As the last poster said, this happens. All but the calmest breeds tend to kill each other off when they meet maturity, and even in the calmer breeds they needs lots of females and space to tolerate each other. Loval craig's lists are full of 'free to loving home' roosters because of this. In modern days it is hard to do what most owners would have done in the past, and that is to make rooster soup.
Unless there is someone locally needing a rooster or you can start a 'parallel flock' I think you might be faced with a pretty hard decision.
If you have the room though, another flock might be a good idea. Or getting more hens, one rooster to about 15-20 hens is thought to be the ratio depending on the breed.