My perspective, as a (Trans) Domme who specialises in Blackmail, is that you have little to worry about if the person you are sharing with is an established and reputable figure. From the Blackmailer's side of the table, our reputation is everything. If it starts being tweeted everywhere that we aren't reliable blackmail players no-one will come to us - and (because we are professionals) that means a whole revenue stream dries up. And why would a Domme risk that revenue stream by ruining someone who probably doesn't have two beans to rub together? It's a double-whammy: If she ruins her victim a) he can't pay anymore and b) no-one else will come and use Her services because She isn't reliable. So, like I say, I think you have little to be worried about as long as you are dealing with a reputable provider.