Will I get sued for breaking my lease?

I offered to take over someone's lease for the remaining two months he had but when I moved in I found out a cat lived there (I'm allergic to cats). He kept two dogs in his room and the odor is just inescapable. I already paid the first month but might run for the second. He has my number and text messages so I think he can easily track me down. This lease is unofficial, not through the apartment