And we're trying to help you.
I'm sorry if I'm coming off harsh, but if you want to be sexting other guys or telling them you took naked pics - you know you were trying to tease them, you wanted him to ask to see them - then you shouldn't be in a relationship. That is honestly okay to enjoy, when you're single!
When you're dating someone it is incredibly disrespectful to flirt with other guys like that (unless previously specified to be okay), and yes you were don't say you weren't. How else would the topic of you taking naked pictures come up?
How would you feel if it were flipped, and he was the one flirting with his female friends like that and acting as you were? You honestly cannot see why he'd be uncomfortable with those friendships?
He's not wrong in that you're stringing these guys along, because it very much sounds like you are.
It does sound like:
he will text her when he's at work but has said he doesn't want to text me when he's at work
That is an issue, why the fuck would he text his ex girlfriend at work but not you? I would not accept that, at all, ever. MAYBE if they had a kid together and it was kid related - but that's part of why I won't date dudes with kids!
I'm sorry but I honestly think he's checked out already, or half way out of this relationship, probably mostly due to your inappropriate behaviour with other guys.
And honestly if he came here with it from his side -
'my girlfriend has sexted her male friends in the past, and i feel very uncomfortable with her having male friends. She told me that recently she told one she took naked pictures and he asked to see them and she said no. I feel this is inappropriate, she's stringing these guys along and disrespecting our relationship. She thinks she's doing nothing wrong and I should back off. How do I get her to realize how much this hurts me and fix this?
He'd be told multiple times to dump you. Or that you should get counselling, and maybe you should move out so you can both have some space, and that he's justified in requesting those friendships be ended because it really sounds like you can't be trusted with male friends!