Did i do the right thing?

this is very serious problem that u r facing just b friend with ur ex & start knowing the secret OF UR EX which he has but slowly & gradually which will make him tense too in future as he did to u &then start blackmailing him that if he spellout ur friend's secret then u will do the same with him but b carefull don't let him know that u hadnot breakup with ur present boy friend GOOD LUCK