AITAH for warning my friend’s friend about a new guy she’s dating?

This past weekend, I went out with my friend, who brought one of her friends along. It turned out that this friend is dating a guy I used to talk to over a year ago. When she mentioned his name and that he was at the same club we were in, I was curious if we were talking about the same person. Unfortunately, we were.

The conversation went like this:

Her: O*** is going...
Me: Wait, O*** who?
Her: O*** *****
Me: Oh.
Her: How do you know him?
Me: I used to talk to him about a year ago, but it didn’t go anywhere and we ended on bad terms.
Her: That’s my man.
Me: Oh, nice.

She then started asking me a lot of questions about our relationship during those two weeks, some of which felt quite personal. I answered honestly but mentioned that I didn’t have anything positive to share. As a fellow woman, I felt it was important to advise her to be cautious. I summarized my experience, expressing that I regretted meeting him, but I wanted her to be careful. I reassured her that I wasn't trying to put negative thoughts in her head, as she had mentioned hearing similar warnings before. I even encouraged her to have fun with him, despite my experience.

Knowing him made being in the same place uncomfortable for me, and I thought she needed to understand how I knew him, especially since they might wonder why I wasn’t around. I do regret saying anything, but given how disrespectful he was towards me at the end, being nearby would have been very uncomfortable. I ended up on the other side of the club for most of the night because I wanted to avoid him, and I felt awkward about speaking up, but I learned my lesson. AITAH for saying something to a girl I had just met?