This girl acted poorly, there is no issue on that. But maintaining anger at her over it is not productive. When you are ready, you should take her call and hear what she has to say. People make mistakes, and should never be defined by those mistakes. What is more important is discovering what she will do now that she knows she has made a mistake. Certainly you don't owe it to anyone to pursue a romance you don't feel, but. You owe it to everyone to allow for the mending of fences when mending is offered.
I confess that one of my biggest frustrations on this forum is the stubborn unforgiving nature so many cheer on. I am not saying you share it, just that most posts here do. How can anyone entertain the idea of building relationships while never allowing for people to error, grow, and change? It becomes a method of self selection, of making sure no one will ever meet the standard and, thus, an actual relationship never have to be dealt with. Don't listen to it.
Take this situation as an opportunity to practice the necessary social skill of moving past a difficult situation and warranted anger, into forgiveness and understanding. It is something one can never practice enough, and a skill essential to your future relationships.
And next time you are in a situation where you want to help a third party, don't let anyone talk you away from it. The best thing would have been to be your true self first - helping the person in the meltdown - explaining yourself to your companion later. Although a very well worded leave would have in order: "sorry, I need you to excuse me for a few minutes, I believe I can help this person.". If that is the real you, then let your dates see that person: the right person will admire you for it.
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Mom to an amazing young adult AS son, plus an also amazing non-AS daughter. Most likely part of the "Broader Autism Phenotype" (some traits).