My roommate is threating to not pay her rent and tie me up in court for the next three months knowing I'm leaving the country.

My lease states that I can't have a roommate, but my landlord, who lives in the building said it was okay to get one. My roommate and I wrote a contract stating how much she would pay and when she would pay it. (the first of the month.) There is no mention about giving a 30 day notice. In New York is it mandatory to do so?
My roommate has threatened to tie me up in court for the next few months, while not paying rent, knowing I'm leaving the country and will be unable to try and recoup the money. If I terminated my lease and left early, could she still stay and battle my landlord? I like my landlord and don't want to burden him with this problem. Could my landlord invoke the one person only rule that's written in my lease, thereby evicting my roommate?
Finally, can I sue for the rent in civil court, considering I'm not the landlord? - Is this your question? Add additional information