Search Results: how do i get my ex to leave his girlfriend

So, my girl suddenly went for lunch / dinner with her friend, saying that she had to get some items from him that he bought in England for her relatve. They talked about his ex and how they practiced martial arts with another couple. And the dude complained that his ex was a very jealous girl and would get mad at him for even talking to another girl. So here's the question she gave him:

Would you prefer a jealous girl that's obsessed with you or an extrovert which would hang around with other guys?

As I know her, she's the jealous type, on the lower end of the spectrum and that more or less likely merely insecure.
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But then to me, its also a subtle statement that if I leave her for another, they will most likely be sleeping around with other guys.
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And then she told me that they Used to be REALLY CLOSE FRIENDS but 'something' happened, (unsaid: they no longer are, but she kept the dinner idea from me till the last minute) and that he told her that he was bullied really badly in a certain type of school when he was young.

*she taught the same type of school and he went to VISIT her and STAYED in the CLASSROOM. he started to curse the students, teachers et al.

Then she got a SMS text message (not WhatsApp) from a number that she hasn't saved. They even spelt her name inccorrectly, and she does not recall she had talked to anyone about the certain museum the sender was talking about.
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But then she was like, oh it should be A or B (another friend who's married but fancies her like crazy), quickly, search online for this museum, i'll tell him. But she has never told me to seach stuff in such a tone and was never that enthusiastic about people asking her stuff.
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Do you think that guy means something special to her? Thank you very much in advance for your opinions and