Don’t have a lot of experience with men and this first one has me confused and sad?

I have a friend and she was studying abroad for a year and while she was gone her older brother began to hit me up to hang out and one thing led to another and I lost my virginity to him. We had sex several times over course of a few months. I took a leave of absence at my university like two months ago to help take care of my grandma who is about three hours away from him but we would still talk on the phone and FaceTime and I visited him once too. His sister came back from Europe like a week ago and she came to visit me at my grandma’s house. She brought up the subject that she thought her brother had a new girlfriend. I asked “Who?” And she said “some girl who is always in his insta stories” and she showed me one of him eating with a girl and I realized he had hidden his stories from me. I got very upset and started crying and she asked why and if I had been with him. She said “I thought you were a virgin?” and I said that I used to be but that I had been with him several times. My friend got sad and she told me, “I’m really sorry if something happened between you guys. My brother’s not right in the head.” All this happened like an hour before she had to leave and I was pretty emotional afterwards so I called the guy and was still crying and asked him “why didn’t you tell me you were dating someone?” and he said “I’m not!” and I asked about the girl in his insta stories and he played dumb and then said that he hid his stories from me because he knew I had a jealous personality and that I wouldn’t understand him having female friends. then I texted him a little later telling him that I was still kind of confused about if he was dating some girl and that I also felt bad that it had slipped to his sister that I had been intimate with him since I think he wanted me to keep it a secret but it was just a lot to keep in after hearing about that girl. He texted “im not dating anyone. Don’t contact me.” I’m really sad and confused about why he treated me like this

5 mo
I’ve been stressing that maybe I will run into him and I don’t know what I should say?
Don’t have a lot of experience with men and this first one has me confused and sad?
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