I would double check the laws in your area but as far as I see it he didn't pay in the amount of time agreed upon. You gave him extra time and he still didn't pay. In the time he was making payment you have been a reptile sitter. You have paid money for power, food, and upkeep. You have also invested your time. If you where running a business of housing reptiles for people you would probably be owed more money then he has paid (just guessing here).

Long story short; I would print out all the emails and save them somewhere safe and resell the PB if you still want to or just keep it. Let him take you to court if he wants. He broke the contract. You're fine. If your heart tells you something else then cut him a break if you want but I wouldn't.

You never know, maybe the wife didn't know he was buying the BP and cut him off financially.

BTW, I'm not a lawyer, nor do I play one on TV. Don't yell at me if what I said is wrong in your area.