Am I overreacting??

So it was Prom night and I went with my (then) bf (now ex). It was at the dinner party when another girl walks past in a beautiful green dress when he said that he was glad I went for a silver dress because "Green is definitely not your colour". I was really upset and didn't speak to him for most of the night, but forgave him a couple hours later. Looking back now, all my friends are saying that he was a walking red flag, and that was just one time out of many, so I am just a bit concerned that my red flag detector is not exactly up to scratch...
Was it really that bad or was I just overreacting?

So it was Prom night and I went with my (then) bf (now ex). It was at the dinner party when another girl walks past in a beautiful green dress when he said that he was glad I went for a silver dress because "Green is definitely not your colour". I was really upset and didn't speak to him for most of the night, but forgave him a couple hours later. Looking back now, all my friends are saying that he was a walking red flag, and that was just one time out of many, so I am just a bit concerned that my red flag detector is not exactly up to scratch...
Was it really that bad or was I just overreacting?

You aren't overreacting at all, a relationship shouldn't be putting you down, a partner should uplift you. Commenting so carelessly on your appearance is cruel at best, emotional abuse at worst. You can do so much better than him, I'm glad on your behalf to hear that he's now your ex.

Thanks you so much - this makes me feel better!