You have to put nonsense like this behind you. I agree with you that the woman was in the wrong, especially because she had a child riding behind her. It's not that she ignored a stop sign, or about who had the right of way. It's that she ignored common sense. Regardless of the law or whether there's a stop sign, one always stops, or at least slows to where one could stop short, and checks for traffic before entering a roadway, whether from a driveway, sidewalk, bike path, or smaller road.

When people do similar to me, I don't argue right of way, I just call out "good thing I wasn't a car" and ride on without bothering to wait for a response.