Someone can relate?

I dated a guy a few months ago and he wanted to get to know my family and my sister and him got along really well, so I gave her his number

Then we broke up and my sister told me they send nudes to each other I'm like ok ouch cause it's my sister and my ex but whatever cause I don't care about him anymore

I recently met someone else and we spend a lot of time on the phone ( we're long distance) and my sister blushed everytime she sees him and was like "oh I need his number looks like we could get along" and I was like nah I'm not gonna give it to you cause I know what you're capable of and she got offended, I talk to this guy about my sister and he legit has no interest what so ever in her.

But my question is has this ever happened to one of you bc I don't know ow how to deal with her she's 19 and sexually active and kinda thirsty 89% of the time

on the other hand I'm 17 and a virgin the guy I'm talking to is 19 (we're not dating yet bc I want to be 18 first but we plan on it and acting like a couple)

Sorry if this is confusing and really long