Did I overreact or was what he did enough to be a dealbreaker?

[Frank]

Dating is all about finding and learning to find the right partner.

To have a good relationship you need physical attraction and compatibility. A lot of the former you can determine quickly, or on the first few dates. The latter takes time. For compatibility you need to have compatible characteristics: goals, interests, values, beliefs, etc. They don't have to be the exactly the same, and some work ok when they are opposite (extrovert paired with an introvert), but they can't be conflicting.

You just discovered his values and beliefs are very dissimilar to yours. He is unkind to someone because of their physical appearance, and he feels strongly enough to be embarrassed to be dating you, and this is a real problem. He is shallow and you are not.

I am sorry to say, but it sounds like, despite the physical attraction you two are not compatible. I think you did the right thing.

Let him find a partner who is also shallow, and they will be happy together. You find someone who matches your values and you will be happier.

By the way, good for you for looking past appearances, and good for you for sticking up for your friend.

I could, I know we all could, use more friends like you.

Good for you!