Wait! So what did Mr Ahn ex did? What happened?

The Ex is just sort of a dick. While Ahn was head over heels his ex’s feelings were not near the same level and he also has some bitter/jealous feelings about Ahn’s acting abilities. Like imagine you’re in love and you overhear people asking your significant other what they like about you? They also guess that it’s because you’re only good at sex. The person you love doesn’t say anything and let’s them say whatever else they want about you... That would seriously hurt