being cheated on (double whammy when you are left for that person) can leave a deep wound. i have some idea of how it feels; it happened to me.
untreated, that wound can fester, and grow, and become permanent.
There is so much anger in me. Anger at her, anger at the situation, anger at the world. I'm posting this so I don't spiral into an angry void.
anger is, of course, a valid feeling, especially when someone treats us badly.
anger is also often a cover for a wound to our self esteem.
there is no external antidote when that is the case.
in other words grumpy, justice, karma, whatever you or anyone wants to call it, arent going to heal that wound. if their relationship collapsed tomorrow, it might feel good, it might be some vindication, but its not going to fix a broken heart.
Detaching is really just a matter of letting go. there is, of course, a great deal more to it, but in essence, it is letting go of the attachment...to the person, to the feelings, to the memories, to all of the actions, good and bad.
on some level you are attached to two ideas:
1. her cheating is a reflection of you
2. her future success or failure is a reflection of you
this is a pretty natural reaction, but its a distortion.
cheating is an act of cowardice and weak will that is a reflection of that person and who they are. it says nothing about the person who is cheated on. dont get me wrong; in my own case, i can understand why my ex cheated on me (i emotionally abandoned the relationship) but that neither excuses her cheating, or makes the fact that she cheated my "fault" or about me as a person.
easy to say, i know. you probably understand this intellectually, but are struggling to internalize it.
the second part is perhaps more difficult in some ways. and its more difficult because of the nature of our attachment. we gave someone the power to make us feel so high, and then so low.
think about it. before this, you probably never gave much thought if any to whether another exs next relationship succeeded or failed.
the hard thing is that people do bad things to others all the time and never pay any price, or at least one that is visible to anyone else. ideally, many (not all and far from it) learn from that and change/adjust their behavior. plenty of others justify it, continue doing it, or are even oblivious about it.
what would justice in this case look like? if she owned her behavior, made amends to you, and never did it again, would that be justice?
if not, consider that this may be about more than justice. it may be about a broken heart.
i dont say any of that to step on your anger, grumpy, far from it. i say it to suggest that you harness that anger and redirect it in a more productive direction, over the things you have control over.
letting go of the things we have no control over can be incredibly freeing.