OP, you're all over the place in your posts. There has been great advice and insight provided in the replies thus far, but your confirmation bias towards this situation prevents you from seeing anything that goes against your already made up mind.
First problem is you're already "exclusive" with a girl after one month. That is nothing. You giving in to her exclusivity demands after dating for merely a month already shows your scarcity mindset and potential oneitis for this girl. Then you do all kinds of mental gymnastics to try to convince everyone how unattached you are to her, and merely with her because the sex is so amazing. No level of sex or perceived high interest from a woman would ever win over my exclusivity after merely a month of dating. That's just showing your desparation for a relationship and is probably why you're in this situation in the first place.
Secondly, it doesn't matter who initiated the call, the fact that what you heard was her rationalizing why "this time would be any different" to an ex, indicates she did not immediately shut him down out of respect for your relationship with her. 4 years of no contact, distance, etc, has no relevance on the matter. Again, your confirmation bias of trying to see her as a "good girl" is poisoning your rational and logical male mind from seeing the blatant disrespect of the situation. No woman is a "good girl" completely. You should absolutely want a woman to be "afraid" of disrespecting you. Her fear of losing you should be the utmost factor in weighing her actions to be a "good girl." That is what a healthy interaction between a man a woman is...the woman's fear of losing her high value man.
Thirdly, your reaction to the situation reveals that you are not in your full masculine mindset. As other have said, your over reaction is a direct indicator of your internalized self worth and self confidence. Again, you try to justify and argue with everyone stating you don't regret what happens or how she perceives it. That's not the problem. The problem is you allowed yourself to react that way which truly shows how insecure you are with yourself and with this relationship.
Finally OP, based on your continued replies and justifications, it's quite apparent you aren't ready for a serious relationship, especially not with this girl. This "relationship" is doomed. If these issues are already apparent after merely a month of dating, there is very slim hope it will flourish into a healthy LTR. Distance yourself from the definitely forthcoming heartache with this woman; work on your self growth; and truly look deep down to see why you have the internal self esteem issues you most definitely do. This forum is all for each person's self improvement through their RP journey, however, you must be open to the advice and help provided. Good luck to you OP.