What would you do?

So here's the situation... I rent a kitchen and cook individual pre-made meals for people, all ordered in advance online. I've done everything right, I'm licensed, I cook in the kitchen, I pay my rent, which is about $600/mo right now. There is a new guy in town who has stated doing what I'm doing, and renting the same kitchen. He says he'd never heard of me and didn't know someone else was doing this in our area, Okay well you're either a liar or a bad business person, but that not my problem. Anyway, he is way undercutting my prices -my product is still better but still- and pushing pretty hard to get out there. I've been suspicious that he wasn't actually cooking in the kitchen and today my suspicions were proved when he dropped off all his fully cooked, fully packaged meals while we were still there cleaning. I'm pretty pissed. I'd be able to sell my meals for less too if I weren't paying $600 in rent each month. I can't decide if I should tell the owners, or let it be, or something else?? What would you do? Anon for obvious reasons...