I've got a few (about multiple exes, not just one. One is about a woman, the rest are about men):

Voting Republican.

Calling me the n-word on MLK Day (he was from West Virginia).

Gossiping about our sex life to his friends.

He opened up to everyone else except me. This is the same ex who gossiped to his friends about our sex life. I later found out he punched my friend's ex-girlfriend.

I had one ex-girlfriend who forced me to try a Ouija Board (she's clearly demonic - she laughed because my hand twitched over the board. And she'd tell that story for many years afterward. She's now an alcoholic, who's been to rehab 8 times and got arrested for public intoxication. Clearly, someone I do not need in my life. Rejection is God's protection). No wonder she's the reason why I stopped dating women.....

Saying he wanted to dominate me in bed. (I'm still trying to find vers guys to date; too many guys see bottoming as being weak or shattering their ego and masculinity.... maybe I need to leave America to find a good boyfriend?).

He punched his mom in the face at 17 years old & was sentenced to court-ordered anger management classes. He later admitted to being a p (I can't say it on here).

I found out he was engaged to a woman, lied about not being promiscuous, and then before I could dump him, I (stupidly) admitted I was in love with him. He responds by blocking & ghosting me. We had an affair for 3 years at that point. He's DL and married with a daughter now. I messaged him a few years later & got blocked.... again.

I almost dumped a few exes over their astrological signs (I'm a Virgo. Their signs were Aquarius, Sag, Leo and Aries).

These are stories I can look back & laugh about when I'm 85, collecting a check and sitting in my retirement rocking chair. (I'm 28 right now, btw. I was engaged 3 times and ended up single, until my current relationship.)