Breakup after sex

I’m sorry I really need to vent. I was with my boyfriend for about 6 months. We finally decided to have sex a few days ago, which was my first time but not his. I really trusted him and felt that we had reached the point for me to give up my virginity. Yesterday I went to his and we had sex again and everything was fine but he kept tilting his phone whenever he was messaging someone which was bizarre for him. He went to the toilet and ngl I checked through his phone. I found messages between him and his friends and he was saying that I’m boring and he doesn’t want to be with me and that he was using me for sex. I feel so lost, I let this boy have such a huge part of me.