Sounds like she's having a bit of an identity crisis maybe. It's possible that she partly identifies with some of what she read, and is confused about her sexual orientation. I've read some compulsory heterosexuality stuff before and it rang true, but that doesn't mean I'm not still attracted to men. It's odd that she would jump straight to strictly defining herself as a lesbian, especially if you two were happy together. Perhaps she is bisexual. She may need some time to figure things out. If she's willing, I would try to talk to her about it and see how she explains your relationship and the connections that you had. Was it lacking a physical connection? I've known women who called themselves lesbians but still dated men. Seems like an unwillingness to accept or consider bi or even pansexuality. Either way, I'm sorry that you're going through this and I hope you can get some answers. She may need time to figure some stuff out, but I hope she can give you some closure at the very least.