I definitely agree with you. You should leave him. Never take/share any of your private pics to anyone.. He should really take the hint and consider your feelings being uncomfortable about doing any sexual things. Him lying about age was already a huge problem. Confront and block, or even better, just straightforward block him
He is not respecting your boundaries about 18+ stuff, and that is a red flag. Also, if he thought it was okay to lie to you about his age for so long, he will think it is okay to lie about other things. You should probably leave him—there are better people out there for you and you should not have to settle.

I'm currently 19 gonna be 20 and I'm in an idk relationship crisis? My current bf is the first ever person I've been in a relationship with, so let me just share my experience because it's really new to me.
He keeps on talking about 18+ stuff even though he knows I'm uncomfortable. I mean, I do read smut manhwa, but talking about it feels gross?? And when I say I hate it, he says stuff like "If I don't talk like this to my gf, who else am I supposed to talk to about it?" kind of stuff. He would randomly ask me to send my ughh stuff?? And when I tell him I'm uncomfortable he jokes around about it, but then proceeds to ask again after a week or two. But apart from this he actually supports me a lot.
Lately though I just feel like I should distance myself from him because he was actually 18 and faked being 20. Mind you he admitted that on his 18th birthday, and I realized I had been dating a minor all along. (Y'all can hate me for this lol.) We met online, so idk... he might even be hiding things about his past relationships too. He told me I was his 2nd but after finding out he lied about his age I don't even know what to believe anymore. And when he was 17 he used to say some bs like, "I love how innocent you are." I wish I could've said "Bitvh, you're 17"
There are definitely positive sides to him and negative ones as well. But I just can't be in a relationship knowing he's been deceiving me and stuff. And since this is my first relationship, I really don't want to break up either.
Please help.