You've said that Harley has been just as abusive towards the Joker but would you mind bringing up some examples or sources backing those claims? I'm just curious, since I haven't really read any comics depicting these scenarios.
Well, I never said she was just as abusive towards the Joker. But I have said that she has stood up to the Joker on several occasions.
After trying to kill her in a rocket:
After trying to replace her in “Joker’s Millions”:
During the trial of Batman (and he didn’t fight back either):
And of course, the time when she almost killed the Joker: