My lawyer advised me to disclose the challenge to my buyers, but also to offer to indemnify them against any suit that John may bring against my company. I had a long chat to the MD who had a lot more insight onto my situation than I ever could have imagined. He has had his own horrible tussle with a Narcissistic business partner in the past and fully understands how destructive this kind of person can be. He isn't thinking 'what kind of a Leader are you if you didn't see all this happening in your company?' Instead he knows the depths to which these damaged people will stoop sometimes and is full of support for me.
Then I consulted my labour lawyer to see if John has a case. The answer is 'No'. Get rid of him immediately! So I spent last night typing out my 'fuck right off' letter. I've sent it to the labour lawyer for final rubber stamping, and then I pull the trigger tomorrow. Here's the letter as it stands now (I know it still has some care in it - cant bloody help myself)