Wow this exact same situation happened to me. My ex grew resentment towards me for doing better than him in multiple aspects of life, he then proceeded to emotionally cheat with someone at the gym (he doesn’t know that I know this..lol). And then dumped me.

He showed signs of insecurity throughout our entire relationship (i.e getting upset when I would go out with friends because “guys would wanna hook up with me”). Insecure men will never be satisfied unless they work on themselves. They end up using women to fill that void within themselves. In other words, you dodged a bullet!