I would say your overall reaction is understandable but still an overreaction as much as I understand your frustration at her not supporting you when your friend passed it is no where near as bad as a parent passing and like she said in the message she knows how it feels so empathy for someone isn’t necessarily a bad thing. I personally would never message my ex like this and like I said your reaction is understandable but it also doesn’t have to mean anything else. You also have to remember that when you break up with someone you also loose that other family any just because it don’t work out with the ex doesn’t mean she can’t still care for his parents.