This feels familiar! Most people will feel uncomfortable being around a person who is upset because often they feel helpless, which can also bring up feelings of shame and anger - this is more about them than you, but it’s almost impossible to parse those things out in the moment. It’s difficult knowing how to help the upset person, especially because there’s a risk they will lash out at us; it feels personal even when it isn’t.
On the other hand, as you’ve likely found, this is a time when other people can seem callous (or reveal their lack of empathy, depending) in an attempt to shut the other person down, so they can stop feeling uncomfortable. Not helpful or good in the short or long term for the other person.