Scared of developing hatred towards ex in the future, advice?

CONTEXT:

I developed intense hatred towards my first ex one month after he cheated, it brought unnecessary negativity into my life. I have no hatred towards my ex, but I fear it'll happen in the future.

HISTORY:

This is my second breakup. I liked this guy from 2018 - 2020, he had no idea, in my head I developed a perfect version of him which caused me to like him more than I should have. He started dating somebody else so I moved on.

RELATIONSHIP:

In mid-2023 we became friends, I confessed my feelings, and he led me to believe we were exclusive. In reality, he was cheating on me for a year with his girl best friend. If he had been someone I met for the first time in 2023, I would’ve walked away immediately. But because I had idealized a “perfect” version of him in my head from 2018–2020, I felt like staying with him meant fulfilling the dream of my 2019 self, finally getting the boy I once wanted. I still don’t fully understand the psychology behind why I stayed.

For another year, he continued to disrespect me, blaming me for trust issues, being dismissive, and saying hurtful things. His ongoing secrecy about new female friends further eroded what little trust remained. The relationship devolved into repeated cycles of blame-shifting, gaslighting, half-apologies, minimizing his cheating, and sudden bursts of affection mixed with aggression. I ultimately ended things because of his lack of accountability, emotional invalidation, past infidelity, manipulative behavior during his exams, and the constant feeling of emotional unsafety.

ERRORS ON MY END:

1. I contacted the female friend he’d been secretive about to confirm the truth in case they were involved, by briefly mentioning about his past cheating. I had already tried to get him to be honest and take accountability, but he refused, shifted the blame onto me, and denied responsibility for the harm he caused. That was the only reason I reached out to her, which he then twisted into an accusation that I was trying to damage his reputation.

2. I anonymously posted on his college subreddit under the dating flair as a way to vent — no names or identifying details were mentioned. The dating culture there is toxic, and reading similar posts helped me find the courage to leave. When he texted saying a friend had seen the post and recognized it was about him, I immediately deleted it, since I never intended to cause any harm and hadn’t expected the post to gain attention. Despite this, he accused me of deliberately trying to damage his reputation, threatened to involve the police, and became extremely aggressive. I apologized even though there was no malicious intent on my part.

3. After the Reddit incident, I withdrew completely because he began to feel unsafe. Right before his exams, he returned promising to change, and I made the mistake of giving him another chance. He maintained “good” behavior only for the duration of his exams; once they ended, he reverted to being dismissive and rude. What began as small, solvable conflicts kept escalating because he refused to take accountability and instead blamed me, causing each disagreement to spiral. Ultimately, his lack of accountability, more than even his mistakes, is what made me walk away.

4. Post breakup, I continued explaining myself hoping for understanding and genuine apology, because I still loved him. But he refused accountability and "sweet-talked" instead. This caused me to over-explain, slowly spiralling into a heated argument, causing both of us to say hurtful things to each other. First mistake, I shouldn't have bothered explaining to someone who is not capable of taking accountability. Second mistake, I shouldn't have said hurtful things when he cornered me. This caused him to threaten me that he will reach out to my family friends with screenshots of my hurtful texts. This made me scared of him to the point of no return.

Currently I'm just scared of him so I know I won't go back, because going back means more emotional harm from him, possible threats, going back means danger more than love.