<human>: Can you summarize the given text in a few sentences?

Tonight I fucked up by eavesdropping on my mother while she was talking to my aunt that lives in Australia. I was in the kitchen making myself a sandwich, while my mother who was on the phone starts talking about the past, which peaks my interest. As I was listening on to their conversation, my mom says " wow... I wonder what would have  happened if we didn't switch children, I would still have three daughters, and you would still have three sons. Was there ever a moment where you regretted swapping children with me?" As this was going on, my mind was fucking blown, I could not believe that my mother is not my actual mother, the "aunt" that I've seen twice my entire life, was my actual mother?!. 

I am currently sitting in my desk eating my sorrow sandwich, all because I decided to eavesdrop on my "mother". I guess I see why my "aunt" treated me so well when I came to visit her. And the thing is, my cousin and I are the same age, only 4 months apart. 

Don't get me wrong, I still love my parental unit, but I can never forget what I just heard.
<bot>: I overheard my mother speaking on the phone with her sister in law, and found out my mother swapped me for my cousin with her sister in law, because she wanted a daughter, and they wanted a son.