He's close with his ex and it bugs me

They didn't date very long (my boyfriend said it was only a couple months because apparently she was a rebound and blah blah blah because the girl he was with before her really fucked him up because she cheated after they were together 6 years. So he hates the one he dated for 6 years. But the apparent rebound who he dated before me they only dated like 3 months but they still get along now)

Long story short it bugs me when they talk to an extended period of time. Like literally she sent him a text asking about who has the right of way in an intersection kind of scenario question and he stopped having sex with me to reply to her and then proceeded to want to have sex. I said no and got off him and started getting dressed.

And without screaming or making a huge fuss I just said I have no problem with you texting her but you could have waited and didn't have to reply right away.

Also she wants to be like my best friend. I've never met her. But a bunch of his friends including her have been bugging my boyfriend wanting to meet me and all that kind of stuff. She literally creeped me on instagram and sent me a DM and like introduced herself saying she can't wait to meet me and said we should go out for coffee sometime and in my head I'm like but you're his ex! What do you want from me?!