My girlfriend admitted that she had a dick in her ass the whole time

I met this girl on ps home, and we had a long romance for several months, or so I thought: of us coming to her personal plum tree pavlon and watching hours of television together, talking about our future children, her days at college and what she learned, our life plans, etc... recently, she revealed to me that she was getting fucked in her ass almost the entire time, and I feel like a jack ass.