I'm very confused and need help.

I'm M29, my fiancée is F25, we've been together for 5 years and engaged for 8 months, with a wedding scheduled in 10 months. Our relationship is monogamous, and we're both jealous about it. I've always been bisexual, and she said she was straight. About a year ago, she started consuming a lot of sapphic content, series, stories, movies, music, and I always encouraged it. She's always been obsessed with love stories, a typical fanfic writer, and it was never a problem for me.

About a month ago, she called me to talk and said she was confused because she might be feeling attracted to women, but wasn't sure what she was feeling. It was a tough conversation, but I was happy she was opening up to me and being honest. I told her I'd be there for her and support her in her journey of discovery, and that she could explore her feelings without feeling guilty, as long as it didn't put our relationship above everything.

But she started acting really strange, posting sexual content on social media, being distant and weird, like hiding her phone or getting scared when I asked what she was doing. For two weeks, I felt terrible, extremely anxious, and scared something was happening behind my back. I missed her affection, commitment, and intimacy at home. And I reiterated my support for her discovery even though I was anxious.

Yesterday, she finally called me to talk and said she had "crossed the line" in conversations with a girl, who was flirting with her and she reciprocated. She acknowledged that she 'cherry-picked' the parts of our conversation that suited her, She confessed to being selfish and unfair, and revealed she was struggling with an identity crisis. But then she said she felt really guilty and regretful, and that's why she was distant, because she didn't know how to tell me and apologize.

She's saying she's really sorry, it was just a "stupid lapse of two weeks," and she's willing to spend the rest of her life making it up to me. I don't know if I can accept that it was just confusion because she chose to do it and then chose to hide it from me, look me in the eye, and tell me everything was fine while I suffered and humiliated myself just for a bit of transparency.

I might be controlling, too. I don't want to get into a discussion about who's right or wrong; I just want to hear different perspectives on this kind of situation. I cant think clearly if its fair to break up over this.