It sounds like you are in a rough situation. If your name is on the lease, you can't break it or you may have to pay in full your portion of the rent and any consession you may have received. Now, you should talk to your leasing agent to see if there is something that can be done. Some leasing agnecies will allow you to sublet the apartment, that is find someone else to live there in your place. If the inlaws say that you can move out and they will assume the lease themselves, then talk to the leasing agency to see if they can get a new lease with your names not on it.
What ever you do, don't move out with your name still on the lease. If the inlaws decided to not pay rent, you would be liable for what they owe if your name is still on the lease.

