I have to say I really don't know much if anything about these thing's so I won't attempt to offer any legal advise but if it's just a matter of the name, as I understand from your post, is simply changing your name an option?
Could you still continue to sell your products but just call it something else? Your customers would still know it's you and you can send out e-mails informing your previous customers that you've changed your name.
I don't know, just seems a bit extreme not to mention crappy for you to have to close up shop completely because of this challenge to the name. I completely understand that fighting it might be cost prohibitive so instead of going that route maybe just change your name and stay in business? If that's an option.
Sorry if I overlooked something and this isn't an option for you. I just hate to see you close down if there are other options that would allow you to continue your business without a potentially very expensive legal battle. I know I'm looking at this from an overly simplistic point of view but that's the first thing that came to mind when I read your post.
I sincerely hope there is a solution for you other then shutting down or having to try and decide if spending all your money to try and fight this "stupidity" to stay in business would be worth it, especially with all the other challenges going on in your life right now.
Truly wishing you all the best!