I [20F] am insecure about my boyfriend [20M] ex-girlfriend [20F] keeping pictures of him/of them together on her instagram page. How can i handle the situantion and ask her to delete it?

CONTEXT: Three years ago, my boyfriend \[male, 20y\] went to study abroad for one year and lived with a host family and another student \[male, 19y\] and became best friends. While he was abroad, he also met his ex-girlfriend \[female, 20y\]. When the program was over he came back to his country and last year he met me \[female, 20y\] on college, and we are dating for an year and in a couple a days, a month as well.

There is a terrible situation happening in my relationship currently; my boyfriend \[20M\] and I \[20F\] are one year together officially. His ex-girlfriend \[20F\] lives abroad and is from another country (Polonia), and they ended things when my boyfriend came back to our country (Brasil).

They didn't had any arguments and ended things nicely, so they keep in touch with eachother as friends, until we (me and my boyfriend) met and started to get know each other. I don't know if she did it out of jealousy or not (prior to us dating officially, she would text him complaining, making snarky comments and liking the stories that he posted of us on instagram. At this time they were already not talking very much due to her behavior) but she ended up sleeping with his best friend \[19M\].

He got super upset (because of the actions of his best friend) and decided to not speak to any of them ever again (he later told me that as soon as we made it our relationship official he was not going to keep talking to her because it was disrespectful to me). But then i found out (today) that she has highlights (yes, MULTIPLE) of both of them together.

There isn't any picture of them kissing, but they were always close (in the pictures) and there even is one that she puts heart stickers. And there is just so may of them, anyone who sees the pictures can tell that they had this kind of relationship. I got really upset and i don't know exactly what to do about it, because its not his fault.

I wanted to talk to her ask her nicely to delete it because it made me feel uncomfortable, but assuming what i know about her personality (the way that she handled the aftermath of sleeping with his best friend was terrible, very low character), i know that she will take this opportunity to mess with me, and also, it makes me look very insecure (which is true, and if she was a nice person i wouldnt mind her knowing that), so im considering asking my boyfriend to do it. But i dont know.

Im struggling because it bothers me so much, but it sounds so fucking silly when i say it out loud.. Im not afraid that if he asks her to do it they are going to talk and shit, but it just doesn't seem right for me, something in my guts is telling me that its not the right choice.

I really don't think that this is an appropriate behavior to have towards your ex (who you're not friends and dont talk at all) who is in a new relatioship for over an year. I trully want her to delete those pictures, how can i ask her that? Or my boyfriend?