<human>: So I have been seeing this guy for a month now and I really really like him. We were supposed to go out last night together for Halloween but I cancelled on him last minute because my little sister called crying because she was verbally and physically abused by someone. 

I feel bad for canceling last minute but the guy got really mad at me. All I said was "I had personal family problems that I needed to take care of".

Anyways, I think that is reasonable enough to cancel last minute. I was thinking of telling him today that we aren't even exclusive and he isn't my boyfriend, so why shouldn't I put my sister first? I get that it is rude to flake but I obviously had a family emergency. I was really bummed out and instead of saying "I'm sorry, I hope everything is okay", he just got pissed. Am I in the wrong?

Summarize the given text in a few sentences.
<bot>: Guy I'm seeing got mad because I put my sister first. Thinking of telling him off but don't know if that is a good idea.