What To Do With Your Bad-mouthed, Scumbag, and Certified Douche Bag Former Boss?

Is your boss like a fat, nasty ectoparasite? Tick - tick - tick!
(Picture is from www.holytaco.com, post by Ian Fortey.)

Or a disgusting blood-sucking leech?
(Picture is from www.desertusa.com, post by Jay Sharp.)

I thought I was going to vomit.  I felt dizzy and saw macaws circling my head.  I guess being hit by a lightning feels so much better than tasting blatant betrayal.  When you hear utter lies about you told by your former boss no less, it makes you feel disgustingly and gravely sick to the bones.  So, what should you do when someone bad-mouths you?

I've got my cauldron, pig's feet, toe nails of bats, black mamba slime, leech blood, mandrake root, and ox bone ash.  I'll hex that demon, I mean, that loathsome, contemptible, tiny man so that every time he spits out lies, huge slugs will come out of his mouth.  My conscience however, could not bear such a wicked revenge.  Plus, I really don't know anything about hexes or witchcraft.  I was just being colorful.  LOL!  But, when you are wronged by someone you thought would never do this to you, your mind becomes a little bit creative.

Okay, being a pacifist, there must be some other way to deal with former scumbag bosses and certified douche bags.  If your former boss for instance, in the interest of protecting his little "cottage industry" (illegal much?) like an ectoparasite sucking the lifeblood out of a legal corporation, told lies and smeared your reputation, because he seemed afraid you might squeal his dirty secrets, what should you do?  What should you do?

I found this passage from the book I have been reading whenever some form of career-related "creepiness" worked its way to my life.  It goes and I quote:

"A bad person who slanders a good one is like a person who looks up and spits at heaven.  His spit never reaches the sky; it falls back into his own face."

The article in the book further explained that there's nothing should be done with these kind of people for everything will take its natural course.  So, basically let them drown in their own bile!   Ohhhh!  Yeah, that's a relief!  Stooping down to their level would be a disastrous mistake.  You know, come to think of it.  The tears, sweat, and blood I shed for my former work were parts of the impregnable testament to the kind of employee (and boss) I was.  So, there's no retort or revenge really necessary.

Thus, going back to the main question - what to do with your bad-mouthed, scumbag, and certified douche bag former boss (or any co-worker, past or present, for that matter)?  The answer is "NOTHING".

Oh well, I just wasted your time reading this.  LOL!  I am curious, if you were in my shoes however, what would you do?  As advised by the book, stay clear of the "spitting range".  Seriously, what would you do?

Postscript: 

(1) I was reminded of my high school days.  My classmates and I would not go home whenever classes are suspended due to typhoons.  There was one occasion when instead of heading for home, we went to Rizal Park / Manila Bay.  The wind was so strong and the sea was clobbering the breakwater.  I couldn't forget the time when I spat (major yuck!), the spit went straight back to my face!  That was one disgusting and very funny moment.  But it actually served a reminder for me not to trash-talk  others (whoa, really? hehehe.).  True story, folks!

(2) The book is by Franz Metcalf and BJ Gallagher Hately.  It is entitled What Would Buddha Do at Work?  101 Answers to Workplace Dilemmas.