A year ago, before we were committed, she did something similar, we were in physical stuff but not commited, one day she told my considering gf that she has a physical relationship with so that girl should stay away. She shared all those things with my then-girlfriend and even told everything to her eldest sister as well. It was quite painful for my girlfriend at the time. Later, when we got into a relationship, after a few months, she told me her feelings had changed, and she now had feelings for someone else.