Has anyone else seen a narc's narcissistic collapse?

The BPD girl my ex cheated with seems to have left my Nex for another guy herself. I hope she doesn't come crawling back to him or let him come back to her. Oh well.

I finally saw what my Nex looks like currently, months after realizing what he was when he broke up with me over text for her.

Deep dark circles, no haircut in months, barely shaven, a bit out of shape. She must've done a number on him. Poor dude seems to sleep in his living room now too. He was also shorter than I remembered. Maybe this was an early Christmas miracle to see the outcome of someone who wronged me haha.

He didn't reply to anything I said when I mentioned BPD ex's name. Ofc. They both knew I found out eventually. He also apparently "never cheated". Didn't even acknowledge how cowardly it was to break up over text or apologize for it either.

Sometimes they reap what they sow, you guys. I hope some of you get to see it. Maybe when it happens, you won't care anymore, which is great.

What was your experience if you've ever seen a narcissistic collapse? Or the aftermath of how a narcissist turned out after one?