This might sound callous, but it's disruptive to have someone crying in the office and sharing their personal drama with everyone else, or becoming a topic of conversation/pity/whatever.

So your boss may have felt compelled to send you home for the good of the rest of the office. It's the normal thing to do. It would be abnormal for him to have expected you to continue working for the rest of the day, both for decency reasons and business reasons.