Definition: Given a real-life anecdote of a complex ethical situation, generate a suitable title that describes the main event/root cause of the situation. Imagine that the given text is a social media post, and you have to write the title of the post, so the users can decide to read the main text or not.
Input: Longtime lurker here, never posted tho! So yeah, I met this girl Sarah close to 2 years ago now, at the end of my last semester at uni and we really hit it off. We started dating after casually going out for a bit, and we ended up dating all the way up until early November 2018, when I found out that she had some sort of FWB type bullshit with a guy we knew at uni, and I broke it off, cold turkey and basically told her to go fuck herself. It still hurts like shit, since this was a fairly long term thing, age considered, and she didn't seem that guilty to me.

We do however have mutual friends so we see each other sometimes, and I kept her on my social media stuff, which is how I found out she was flirting with some new guy, Tommy. Tommy's actually a nice enough dude, and since I can't say I trust Sarah one bit, I messaged him telling him about the cheating and all the bullshit she did. He didn't believe me, but we met last month at a party, in which I pulled him aside, and told him all about her, and by the end of it, he seemed pretty turned off on her, and he cut it off a few days later.

Despite this, and the fact that things seemed somewhat serious between Tommy and Sarah, she had a new guy just last weekend, at another party. This guy was pretty decent, and when I caught Sarah looking my way with a shitty expression, I just lost it, and told this new guy all about her. They got into an argument, him saying something about diseases and storming off. The room was divided, some were on my side, some were obviously pissed at me and Sarah was FURIOUS. 

She basically went on a huge rant about how I'm a jealous asshole who can't let things go, and all this shit about me being controlling and possessive, so I just kind of left in the middle of her lecture. She's DM'd me on a bunch of apps, basically berating me/asking me why I did that, to which I've not really responded outside of a "K", or a thumbs up. A couple of her friends have said similar shit, and called me sexist and all that bullshit. 

So, is she right? Am I a possessive asshole, or was I in the right?

ruining cheating ex's chances with other guys