Do I have a right to be upset? is this cheating?

I just found out my now-bf slept with another girl in the early stages of our relationship.

For context, we met on Tinder, had been on a few dates and talked all day every day. We had both deleted the app. He told me not to speak to other men and said that he wasn’t speaking to other women… and then he slept with one on a trip with his mate during that time. He said ‘I miss you’ everyday etc and kept asking for me to come. He posted a pic of the girl and him holding hands on his story and removed me from seeing it, having posted me in the background of his stories previously.

We never had the ‘will you be my girlfriend talk’ but always said how we’re not seeing other people. I’ve just found this out almost a year later. We were not official dating but I didn’t kiss any men during freshers because he told me not to. Meanwhile, he was sleeping with people at Edinburgh freshers.
Do I have a right to be upset? is this cheating?
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