My question involves a roommate in the State of: Illinois

My wife and I are on the lease and obtained the verbal permission of our landlord to have a roommate live with us in our second bedroom from October, however she was not officially on the lease as she was not sure how long she would be staying. In May, she informed us that she had decided to stay with us until the end of our lease in October. She paid rent for the month of June on May 31st, and then left on vacation to her home in Mexico. On June 13th, she e-mailed us June 13th and informed us that she decided not to return as she got offered a better job in Mexico, and that she had insulted her American employer so as to get fired, and subsequently had her visa revoked, preventing her from returning to the U.S. She further informed us that she had given her key to a friend of hers and asked that friend to come and gather the remainder of her belongings. She is now asking for a refund of her half of rent for June, as well as her half of the security deposit.

While nothing was put in writing, I do not feel that she is entitled to a refund of the security deposit, as she had agreed to stay until October, and abandoned us early. As for rent for the month of June, we feel that she is not entitled to a refund as, while she was not physically in the apartment during the first half of the month, she had not informed us that she would be leaving, and did not move her belongings out until after June 14th. We feel that her failure to give notice after previously agreeing to finish out the term of the lease has disadvantaged us financially as we did not have an opportunity to look for a new roommate for the month of June.

Ultimately, I'm not too worried about a non-citizen who cannot reenter the U.S. attempting to enforce a verbal agreement, but I wanted to make sure that I am not overlooking anything as the friend to whom she gave her copy of the key is a rather "vindictive" woman who is angry with my wife for not being able to get out of work to pick her up from the airport.