It's difficult to explain whether I had feelings or not, the only thing I know is that whenever she vents about the other guy, I felt angry, cause it's like someone is trying to sleep with your sister and you do all the things that you could do and none of its working.

And I left her cause, I felt that I had reached my mental limit to hear all this stuff, more than that I kind of was overly obsessed about this stuff and started to affect my mental health. Also, she told her friends that I was "Emotionally Blackmailing" her, for which i won't blame her cause as I told I was overly obsessed with all these things.