A little off topic, but I was inpatient with this girl years back with very similar diagnoses to me (an eating disorder-most relevant, bipolar-we were both manic and had no judgement, BPD-there's a certain mindset in this one that's at play for sure), and we talked like twice, but we were kind of competing to see who could be "sicker"--skip more meals, sleep the least amount, be forced the most injections, etc. It was super messed up.

I mean, if you leave out the middle part (putting in tiny parentheses because my brain ain't workin right now) your situation gets:
(using revenge as motivation)-> getting super fit & posting shirtless selfie-> (posting pic to rub it in their faces)-> feeling better.

So I think it's a good idea, but I'm the one who just wrote the first paragraph of this post, so..."don't follow me I do stupid things."