I'm calling BS here - this sounds like a lot of Quacking to me. A lot of drunken quacking. Take 3 long, deep breaths & relax for one minute......
Is there any validity to his claims? If not, I really wouldn't give him the power of thinking I was scared of empty threats. In reality it takes a helluva lot more than one drunk quacking off for the police, IRS or any other agency to pursue claims like this. He'd need to present cold, hard facts with some kind of evidence to back him up. Can he actually provide that & stay sober long enough to convince them?
I'd ignore, ignore, ignore & alert your family that he's up to no good so you are all on the same page regarding his threats. Don't respond, but keep documentation of ALL of his ramblings. IMO all he's after is a big, emotional reaction from you. He's trying to draw you back in. ((((HUGS)))))