I'm really sorry this happened to you, but unless they are mentally disabled this was a deliberate attack on you. 
 
Maybe you don't want to discuss this on a forum but you mention inlaws, and how they never understood how you'd spend money on the tank.  Without any knowledge of the situation I would guess they don't like you married to their child or just hate you for some other reason.   
 
Again real sorry this happened, I can't imagine how devastating.  I know this is Canada, not America, but maybe you can consider taking legal action against them?  No idea if you would have any kind of case (when you hire a tanksitter they usually have insurance), but this is not some kind of mistake, its a malicious attack on you, and what you love. 
		
	
		
		
		
		
		
	
		
		
	
	
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