What do I do. Am I overreacting

he told me to make an insta so that he can send me reels. I said sure. Ended up seeing comments from a girl 5 weeks ago saying “bae” “I miss you b” “🙋🏻‍♀️” and after I sent him the ss saying she’s beautiful and I rather not waste another 4 years of on and off talking he tells me to “calm down” and that she did it “on purpose” and was legitimately laughing in my face. He’s sent me pics of girls in the past while, he’s told me things etc. we got into an argument a few times within the past 2 weeks, and honestly this just did it for me. I’m so upset. I feel like I’m the problem. She was beautiful. She has a beautiful elegant aesthetic. Yet he dares to tell me “you’re the only one I talk to I dropped all my hoes for you” no bitch would comment those things if she didn’t feel some time of way or if there wasn’t anything going on. Idk what to do. Did I overreact. Am I retarded? Should I just stop trying. Heart’s definitely in my ass rn I could throw up.