Talk to a lawyer and be prepared to spend money if you want to keep it. First use is a strong defense, but you will need to defend it. If you have similar pro

Talk to a lawyer and be prepared to spend money if you want to keep it. First use is a strong defense, but you will need to defend it. If you have similar products and can show first use, as you claim, perhaps negotiating a sale of your entire business including the domain would be something to offer them. Usually this kind of tactic happens because they've looked at you and guessed you don't have financial capital to defend yourself. Unfortunately, because it's very difficult to prove they're acting in bad faith, there's likely no way to recover your costs of defense.