im 18, "J" is 39.

We meet on a dating site and i expressed in the third message that im not interested in jus hooking up. im interested in a relationship, a very serious long-term relationship. he said he wanted the same thing but later that night he asked for a picture of jus my regular self and i sent him one and he commented on how you could see my nipples. (it was a very huge sleeping shirt so idk how he could see them) i expressed that his comment made me uncomfortable and he said that he was just "telling the truth/saying how gorgeous i am" i told him that if he wanted to say that he shoulda jus said how i look great and that my body didnt need to be mentioned.

he did apologize and we talked for a bit more until we switched over to texting on imessage. our conversations weren't that great bc we have different work schedules but they were good enough but eventually plan a date. but around the time of planning a date, his text messages changed and he was more or so trying to have sexual conversations or get me to send pictures. which i told him over and over again that i wasn't interested until we're in a relationship.

eventually he told me that if i was willing to do it with other people then i should be able to do it with them. i told him that i only do those things because i felt like i had to for them to like it me, which in the end they never did.

his words doesnt sound right and i feel like he's trying to manipulate me, any advice ?