He dumped me over text right after taking my virginity

Hi friends,

This is more of a rant but would also love to hear your perspective of advice. Me and my ex (both 23 y/o) were together for 4 months. I am late to the sex world because of endometriosis and he knew that so we agreed to take it slow. We had sex and then a few days later did again. The second night a guy from forever ago texted me while I was at my boyfriend’s house and I told the guy to essentially leave me alone. We hooked up immediately afterwards. I told my now ex I loved him before I left. Fast forward few days I get a text out of nowhere saying he feels disconnected after that night and that he was upset about the guy texting me. He dumped me and now I just feel gross and used. I know this says little about me, but I’m having a hard time not feeling taken advantage of. Any words of advice?