I know this reply is late.
But honestly, as cliche as it sounds, the best revenge is moving on with your life and becoming happy again. By putting them out of your life, and them no longer existing in your world.
This is different depending on the situation. Because while yeah, I think distance usually is good for all break ups, sometimes you want to stay friends after time passes on. But in some instances where a partner or friend betrays you, those are people you no longer want in your life (and there are cases even when there isn't betrayal, where it's better for ones health to not be around an Ex).
But in this case, I def think it's better for them to never be in your life again. And you know this. So if that is the guaranteed outcome, then the best thing to do is to completely disconnect from them and put them out of your life completely. While getting "revenge" might feel good in the short term, it almost always backfires.
Most of the time when people cheat, or ex partners start dating again, they are moving on with their life and finding happiness and are probably are happy. You trying to contact them, trying to be petty toward them, that often just makes them feel validation and stroked their ego, because it's someone that still thinks about them, when they aren't thinking about you anymore.
To them, it's a sign they have moved on, and you haven't. That gives them the upper hand and just strokes their ego. The ONLY way feel good about a break up, is to move on and start dating again, to be happy again. You might even have a partner regret the break up. Or get jealous if they find out you are happy again. That last bit isn't important. Because while that would feel good, it's still petty.
But my point is, in the above situation, there is a possibility of someone of revenge. Whereas what OP is doing, there is almost no chance. It could actually really backfire if they decided to respond (I've seen cases where an Ex records audio of them getting fucked). You get my point. Although chances are, they will probably just ignore you because you mean nothing to them anymore.
TLDR; MOVE ON! Only way to get revenge is to move on and completely erase them from your life. Move on and find your own happiness again.