What are some lawful acts of revenge?

I'm referring to legal ways to reveal a person's true character. A man I have known for more than twenty five years has become vile and hateful in his personal life while wearing the garment of a prosperous and successful financial officer in a major corporation. He refuses therapy for his drinking and gambling, berates his soon to be ex-wife, allows his teenage kids to drink, smoke, and do nothing more than tell them not to wake him up when they get home, threatens to pull spousal support whenever things go against his wishes; the list goes on and on. I want people to know his true character, not just the shallow image he is so proud of. I am not interested in childish pranks or things that are against the laws on the books. The truth is sufficient to shine light on what he has done to bring misery and heartache to those who were closest. Success stories on what you did would be welcomed.