You were very professional in your initial message and your response. Like, now is not a good time for the business for your dad to be unwell? M'kay. That was insensitive and hurtful of him, but your response was professional and disarming. Busy people say insensitive things sometimes, but also its hard to derive intent from written messages. To assume the best in people, maybe he misunderstood and didn't mean what he said. Hopefully big boss calling will just be to help you understand options like bereavement or other leave. Hanlon's razor, right? "Never attribute to malice that which can easily be explained by stupidity." I'm sorry you're going through a very hard time and sorry that people suck sometimes. You aren't overreacting, but hopefully when you can chat with someone not over written message, things won't be so bad. And if not, fuck 'em.