This has nothing to do with animal law - moving to landlord/tenant.

You violated the terms of your lease. It seems the smoke detector went off and your LL, illegally, covered it. Make sure it is working now, and...

You are not required to open any attachments on an unsolicited email.

This is not a contracts issue - moving to privacy, where it belongs. At this point, you show no damages.

Cameras are your friend when dealing with neighbors like that. You may wish to acquire some.

Moving to landlord/tenant, where this belongs. Per your post, you are free to leave with no penalties, so lack of damages seems to be an issue....

You should also report the illegal apartment to the building inspector, when evicted.

As you have no lease, you are a tenant at will. He is required to give you thirty days notice.

Retain counsel versed in animal law. Use the Avvo search tool and/or your county bar association.

This is a contract issue - you had a verbal one, and your sister broke it. She owes you a refund.