Gravano is a real scumbag, but I do agree he is sensationalized. At the bottom of this article is a list of all the murders he admits involvement in. He says the only person he personally pulled the trigger on was Joseph Colucci.
http://www.nydailynews.com/archives/news/no-20-bull-et-gravano-charged-1980-slay-article-1.670295

If you read his book he comes across as a dutiful soldier, committing murders just because his boss said so, even if he didn't believe the person should die. But if you look at the facts surrounding some of the murders it looks very suspicious. He's involved with killing Milito, then takes over his business. He's involved in killing DiBono then takes over his business. He's involved in killing DiBernardo then takes over Local 282.

He was involved with killing his brother in law, but his only involvement was being told it was going to happen by Frank DeCicco. If he was going to lie, why bring this up at all? It's not like the Feds had evidence that he was involved. He could have just not mentioned this incident and then he would look better not having his brother in law's name on his kill list.

People say he killed way more than 19 people. But those people are Anthony Casso and Richard Kuklinski. If he was going to lie about his body count, why include his brother in law? Why include some guy called Jack who's last name he doesn't even remember?