Do not rejoice when your enemy falls, and do not let your heart be glad when he stumbles; Prov 24:17
You should exercise caution when talking about the troubles of others. I know you do not care for your ex; after all, he was abusive or she had an affair.
You may consider others an enemy – a competitor in business, a rival in a race, or someone that bullies at school.
If trouble happens their way, do not rejoice. Be careful what you say, what you post on Facebook or what you Tweet.
Repay no one evil for evil. Have regard for good things in the sight of all men. If it is possible, as much as depends on you, live peaceably with all men. Beloved, do not avenge yourselves, but rather give place to wrath; for it is written, “Vengeance is Mine, I will repay,” says the Lord. Therefore “If your enemy is hungry, feed him; If he is thirsty, give him a drink; For in so doing you will heap coals of fire on his head.”
Do not be overcome by evil, but overcome evil with good.
The best thing to do about someone that is your adversary – pray for them!