Recommend you don’t spend “ thousands of dollars to hire a lawyer and file a response” on something that you find very slightly worrisome.
Again, I think you, too, are being suckered into spam. Plenty of people fall for spam scams. It is nothing to be ashamed of. Think of all the people who fall for the fake IRS phone calls.
But learn from it: keep your guard up when you get emails, phone calls, or text messages from strangers.
Anything legally binding in the US will come to you via snail mail.