I need advice im just sad

I like this guy, i thought it was mutual because he was always flirting with me, touching me and getting really close to me, getting jealous about other guys, staring at me and complimenting me. Constantly talking to me and so forth.

But he went on holiday last week and i found out he's slept with another girl and hes allowed don't get me wrong because we're not together. But he also told me he liked me before he went and confessed his feelings and i just feel really dumb right now.

He hates it when other guys are hitting on me and talking to me but i dont think i owe him anything anymore.