I left my last job on bad terms last year. Boss was an absolute nightmare, compulsive liar, creep, and to top it off I found out he had been under paying me for years and lying on pay slips/tax etc (I won a case on this). I handed in my resignation, left with immediate effect after he bullied me for weeks and weeks in an effort to make me leave before I could bring a case against him. Luckily all has worked out brilliantly, I am in a much better job and happy to be out of there.
I had heard from a few old contacts that he had been telling people he had to "let me go" and then today I have heard that he has been telling people he sacked me for gross misconduct 
. I'm furious. Not only is it completely untrue, it is embarrassing and tarnishing my reputation in my field.
I don't know what to do about it. Contact him? Contact a solicitor? Leave it? I know a huge amount of pretty nasty stuff about him I could have easily told people and I haven't said a word (like any normal, decent person). AIBU to be so pissed off about this or should I just shrug it off?
Name changed for this as it is recognisable to a few people IRL on here.