I (M39) love her (F40), but her (F14) daughter is actually my biological daughter too.

This a throwaway account. <br><br>I (M39) have been dating a woman, Wendy (40), for the past 3 years. We have been living together since last year. I love her. She has a daughter, Bethany (F14), from another man. I’ve grown very close to the girl. <br><br>I’ve just learned that Bethany, my girlfriend’s daughter, is actually my biological daughter too. <br><br>In 2007, I had a one night stand with Wendy. I had no idea she got pregnant from that night. We didn’t have any sort of contact ever since and I haven’t seen her again until 3 years ago. <br><br>When we started talking again, I learned she had a teenaged daughter, Bethany. Bethany’s dad died in a car accident when she was 2 years old. I always thought she was talking about the biological dad, but actually it was Bethany’s step dad. <br><br>Bethany looks A LOT like me and my side of the family. But when I asked Wendy if I could do a DNA test with Bethany, she told me that it was unnecessary because she knew Bethany wasn’t my child. <br><br>Then last weekend, I found out the truth. Bethany and I went to get some food. The worker is an old friend of mine. When she noticed last name on my credit card, she started making small talk about how when/where we met. I was confused until she told me Bethany was a middle school classmate of her daughter’s and that Bethany did a project on her family ancestry last year. My friend thought it was a funny coincidence that our daughters went to the same school. <br><br>Long story short, I saw the project that had actually been left on our fridge - pictures of Bethany’s ancestry, which included me. <br><br>When I confronted Wendy, she broke down crying and told me that back in the day, her parents threatened to disown her if she told me she got pregnant from our hookup. She said she had no choice but to do what her parents said, and that was her reason for not telling me. She also said that looking at Bethany reminds her of me and it hurt to look at her everyday knowing I wasn’t there for her. <br><br>But when we reconnected 3 years ago, Wendy said she decided to keep the truth from me because she was older and wiser, and didn’t need to listen to her parents anymore. She said she was worried that if I learned Bethany was mine, that I would get too close to Bethany and Wendy would lose me when I inevitably couldn’t look past the fact that Wendy kept Bethany from me. <br><br>This has left me reeling. One part of me feels like Wendy did this for Bethany, to give her a good life. The other part is angry that she hid Bethany from me. I don’t know what to do. I’ve been ignoring Wendy since our fight. I don’t want to leave her, but I don’t want to ignore this and move past it.