I'm not going to clutch my pearls; your feelings are totally normal. It's universal to feel schadenfreude when scuzzy cheaters get their comeuppance.
But the sucky thing is that you cannot control this. How can their hearts break when their hearts are shrunken little underdeveloped things? They're like that gross little baby Voldemort when Harry killed the part that lived inside him. If they had nice, big, healthy, normal hearts, then they wouldn't do the dumb shit they're currently doing.
But having a shrunken little Voldemort heart as you go through your one precious life is pretty good revenge. They're the pathetic heroes of a Greek tragedy. They could have had great lives, and instead they've torpedoed everything they ever truly loved. Are you getting my drift?
The other betrayed spouse and I did team up; it's how we uncovered the affair. And I used my knowledge of his custody schedule to trick my ex into getting on opposite weekends with his girlfriend. It's now been a whole year of opposite weekends and every few months my ex will say, "Oh, I am hoping we can switch our weekend schedule," and I say, "Oh, why? What problem are we trying to solve?" and he runs away like a coward, unable to say the words, "I want to have weekends with my girlfriend." His guilt and conflict avoidance are that great. I also have a theory that he doesn't actually want to spend all his weekends with her, but he can't tell her that obviously.
And everything else in his life is similarly terrible. He's a walking Greek Tragedy. He bought an expensive house four days after he suddenly left me, and it has a flooding problem and smells weird and he lost power and heat during the blizzard. The dog joined the efforts and keeps peeing on his rugs. His children now despise him and call him "that guy" and [first name] instead of Daddy. He developed this medieval skin wasting disease and all the skin on his face fell off. Literally one month after he left me (my doctor thinks it was probably triggered by moving into his new house), whoosh, there went his face skin. He's gone from "drinks a lot" to alcoholic territory. His AP-turned-girlfriend is a terrible person who emotionally abused her ex and has never once admitted to the affair, even though my ex confessed, lol. He told her he didn't want to be tied down and forced her to "date casually" so he could see other people, and he sexually harassed a friend of mine thinking she would hop in the sack with him. The girlfriend wisely joined the "Are We Dating the Same Guy?" facebook group. She went from married to a nice, sober, Christian man, to agreeing to let her cheating, alcoholic boyfriend with no face-skin see other people. Congrats?
So look, I hope all the skin on your stbx's face falls off too. It didn't not help? But, here's the horrible thing about being a grownup and all that . . . it also didn't heal anything. That's all internal work. And as you do that work, you realize that it would suck just to be a person who would run out on their spouse and kids, even if their house never flooded and their skin never fell off and their kids never hated them. It would still suck because they would waste their one precious life on superficial stuff.
I'm all for natural consequences. And maybe for a little harmless mischief, like my weekend swap. But you really don't have to worry about vengeance. People like this bring it on themselves, one way or another. And as much as you want them to hurt, they won't, because they have wrapped themselves in six million layers of denial and delusion.