Is this considered cheating in a certain way?

So I met this guy last year in may and he lives in another country for school but whenever he came to spend vacation here for or short breaks such as spring break, we would always see eachother. While he was away we would talk and snapchat eachother everyday and he has told me deep things about him and so have I. We really like eachother (or at least I thought he liked me), but he is in town now for spring break and I find out thay he went on a dinner date with another girl that he just met for the first time here, but they were talking for 2 months through social media. He never told me anything and I feel really bad, mad, and used. We are not oficial but I thought we had feelings for eachother and I swear I NEVER would've expected him to do this even though we are not in a relationship. Now im just going crazy because I don't know what to believe because he was literally the best guy I ever met. And as crazy as it may sound, im still not over him and im willing to keep fighting to find out the teuth. I dont want to bekieve that this boy doesnt have the heart I once believed he had. Please help guys, im going crazy and I need major advice. Btw we talked after this and he was like I dont know what to say but we are not in a relationship but I know I just made a bif mistake.