I live in Ohio and was in a relationship for over 4 years. My ex bought a house while we were together and I live there. I signed a 5 month lease agreement to stay until Feb 2011 but it is rapidly becoming a hosile environment, is there any way I can break the lease?

It isn't clear who is living with whom, whether the ex is an ex spouse, and what is meant by hostile environment (attack of the killer bees, what?)
Generally no, you can't get out of a lease because you are fighting.

You have a contract with your landlord. This contract is called a lease. Assuming that your ex-whatever is a different person than your landlord, no, you cannot "break the lease". Did your landlord do anything wrong?

it is rapidly becoming a hosile environment, is there any way I can break the lease?Hello me:

Maybe. If you can get a restraining order, that will break the lease automatically. You can't do business with people if you can't contact them.

excon