Yes. It's illegal for anyone to impersonate an attorney or any other officer of the court. It's also illegal for them to make false threats, such as threatening to sue you when they aren't going to or threatening to have you arrested (which is an authority that no debt collector or law firm has.)
It's a good bet that there will be no lawsuit filed against you after 5pm today. If I were you, I'd file complaints against them with federal and state law enforcement and I'd retain a consumer law professional and sue 'em for fun and profit:
Report this attempt to extort money from you with the following agencies:
1) The FBI at
http://tips.fbi.gov or call the local FBI field office
2) Your state's attorney general, the contact information for whom is at
www.naag.org3) The Federal Trade Commission at
https://rn.ftc.gov/pls/dod/wsolcq$.startup?Z_ORG_CODE=PU01For more information on protecting yourself from outlaw debt collectors and suing them, check out these websites:
http://www.budhibbs.com/First.htmhttp://www.naca.net/debt-collection-abuse/http://www.fairdebtlawyers.com/http://www.myfairdebt.com/http://www.consumercounselgroup.com/