Should she have acted like this?

People are not always in control of their emotional reactions. Give the woman a break. Her child was injured and in pain, she was not really in control of the situation when she probably felt she needed to be, and even other pressures like wondering if her other kids will need a sitter, what her own Mom, Dad or husband will think of what happened, and even how the kid's medical bills will be paid for if her budget is tight...Your friend needs to get over it (he may get upset sometime in a way that isn't cool and have to live with someone else's displeasure -- who knows). And she's not your mom, so who cares what you think?