You can sue him for the agreement to pay rent and for your amount of the down payment. Also custody of the dog needs to be worked out. You can't do anything about support if you were not married.
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The Marvin case says you can sue... but that case and such situations general say it's not likely to sort you out. Your only easily accessed "rights" and to dispose if the belongings and MAYBE to sue in small claims court ti get your dog back. Not every human error can be fixed by a lawsuit, Boston Legal (a show I love BTW) notwithstanding.
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