I think grief turns to anger because losing something can really feel not fair. It's not fair that things turned out how they did, and you have no control over it, and it's frustrating, and so these emotions mix up and become anger. That anger can be directed at self, at the event, the other person, their stuff.... it's normal part of grief. To be angry that you lost what you had is normal.

It's good you controled yourself and didn't destroy her things.