I'm not sure how the law works in the US, but just as the new owner is using breach of contract in his defence, I'm quite sure you could play the same hand.
You have a legal binding contract in place which allows you to have pets. By changing that contract, all parties concerned have to agree. I have just confirmed with my boss, that by law, the terms and conditions of the contracts cannot be changed with the sale of the building. If the new owner wishes to change that contracts, new contracts would have to be signed, which would then mean the original contract and cancellation fees of the lease would be voided.
I would definately get legal aid in this case, I'm sure he isn't allowed to do what he is doing. Your lease has to run is full term as is with no changes. If however when you renew your lease he wishes to change the clause relating to pets, he has the right to do so, but then you can just give notice and move without any penalties.
Hope you come right.
YEAH!! What she said!!
I'm pretty ignorant when it comes to the law, period. But contracts are generally meant for the protection of both parties, right? So one person can't just screw over the other person when the mood strikes him/her.