<human>: Can you give me the gist of the text in a nutshell?

Hey guys, would really appreciate some advice. 

My (F18) little sister (F14) has been posting increasingly "sexier" pictures on Instagram and Facebook, the worst being this morning where her cleavage is clearly the focus of the picture. I've tried telling her it's inappropriate but she doesn't listen to me and thinks I'm just being annoying. 

For context, our relationship isn't the best. I had severe anorexia a few years ago while we were both young (15 and 11 respectively) and it really threw a spanner into the works of our relationship. Then a few years later I had an abusive girlfriend who groomed and manipulated my sister against me and we're still recovering from the aftermath of that too. As such we aren't super close... Also I looked after her all the time growing up so I feel more like a mum than a sister to her and I don't like talking about sex/boys/hearing her swear etc like most sisters do because it feels like she's my kid. She also finds me naggy and "mum-ish". And she's pubescent and super irritable/emotional/always picking fights at the moment. I joined MMA classes with her to bond and also let her deal with her anger problems but I work too much to make the classes these days. 

I'm worried about her safety, I've been preyed on by older men when I was her age (like 30 year old dudes when I was 14) and I don't like her putting these pictures up for everyone to see, I know she's learning about sexuality but the internet isn't the place to do that. How do I get her to take down the pictures without driving her further away from me?
<bot>: little sis posting suggestive pictures online, I'm worried about her safety but we're not very close and she doesn't respect my opinion