Guy advice please

So I’ve been talking to this guy for awhile. I really like him but this morning I woke up to him posting a photo of another girl on Snapchat talking about how he can’t wait to see her next weekend and all this other stuff. I called him out on it and he said he did it to piss people off. The person he wanted to piss off was me because I apparently opened a snap from him in the middle of the night and didn’t reply. So this was his way of getting back at me. Am I wrong for being upset and angry about this?