I agree with you, that is what she is saying.
Did you choose to be sexually attracted to members of the opposite gender, and conversely, sexually repulsed by those of the same?
Without going into gory details, yes. I find the thought of kissing a guy extremely repulsive. Could I choose to be the other way, or both ways? As a happily married man, I have no reason to, but I certainly know people who have.
I specifically tailored the question to elicit a personal response from you. Not what your buddies might be asserting, but what you personally experienced. Growing up myself, I certainly was attracted to girls and was repulsed by ANY thought of boys. That's the way I was. It wasn't something I chose. Could I have, after my initial impulse, have chosen homosexuality? I don't know nor do I care really. My point is, without any conscious effort I was a specific way. It seems you were too.