You can ignore the stuff from the CEO, yes. But once you get a letter from a lawyer you should at least have a lawyer look it over and possibly draft a response

You can ignore the stuff from the CEO, yes. But once you get a letter from a lawyer you should at least have a lawyer look it over and possibly draft a response. It can sometimes hard to tell frivolous vs. serious letters, and ignoring a serious one is not a good idea. Given any sort of emotional attachment to your business, and lack of legal experience, you might not be the best person to judge the situation.