your guard completely shut her down. once she tried to stack, you took a nice armbar. done and done. the fact that she is promoting that is just poor. hurting someone is something dishonorable in any context. peoples emotions get the best of them (especially when they are losing) and they go back into "Caveman Mode"
if her coach is saying that this is ok...well that just goes to show the how grimy he is.
if one of my students did that, I WOULD call for disqualification. sadly, people get off on that. those are the same people that kick dogs and beat up people smaller than them.
dont kick yourself over something like this, thats just her excuse for poor jiu jitsu.
and next time...hook the leg

either way, unacceptable and intolerable on her and her coaches behalf.