from the whole thing as peacefully as possible since they work together.
Then she should basically make it look to the world like she's forgotten he exists.
Or even be friendly enough with him to let him spend lots of money on her (his will matter later).

All the wile, secretly she's finding a really sly way to get him fired, like burnt-bridges fired.
Then he'll turn to the drugs more heavily to cope, which will take up any money he has saved.
Then he'll have to resort to desperate acts to fund his drug habit and
hopefully hit rock bottom so hard his body bounces off of it.

Then she should stroll up to him when he's a 90lb zombie on the street and say,
"Damn. Look at you. What happened?" Then smirk and walk off without even looking back.


OR she could just live her life well while he continues to frack his up.
That's always the best revenge.