I know it's not helpful at this point, but you really should have had a relationship with a lawyer already. But now is the next best time. This is just the first time you're running into issues. As you grow, you're almost guaranteed to hit more. You'd also be smart to have a lawyer available to review all of your intellectual property, terms of service, privacy policies, etc.

I'm just a solo punter myself, but having my legal counsel already setup, knowing that I can call them at any time, rather than having to scramble to find someone in the moment a problem happens, gives me a lot of peace of mind.

Given how you're positioned as an Open Source company, maybe the Electronic Frontier Foundation can help you find someone good.