Broken after an affair break up

Not really sure what I am doing on here really but feel it would be good to be among people in a similar position to me. I was in a loving 13 year female gay relationship that was perfect until I fell in love with my best friend, who also fell in love with me back. She is openly bisexual but in a relationship with a man who she admitted she loved but was no longer in love with and had not been intimate with her for many years.

We embarked on a 3 month affair that was amazing, not just in the bedroom but because we were best friends too, talking all the time and hours would feel like minutes. We both knew it was wrong but felt we couldn't leave our partners because of not wanting to hurt our families. Eventually however last December we got caught and the affair ended. We were both devastated and have kept coming back to each other as we just couldn't bear to be apart. However whilst I was prepared to leave to be with her, she kept saying she wasn't ready and didn't know what she wanted. However in the last few weeks she seemed to change and last week she decided that we should tell our partners that we were in love and were going to be together (admittedly after a few drinks) Her partner (male) didn't react or care less and had basically given her carte blanche to be with me as long as she didn't leave him. My Partner was devastated.

Unfortunately the next day she was back to being confused and I gave her the ultimatum that we couldn't carry on like this, it was now or never and for her to have a think about what she truly wants. Throughout that week she continued to message me constantly, saying she missed me and pretty much indicating she was going to choose me. However the day before the week was up she text me to say she wasn't ready to leave and was sorry for all the hurt. We met up again that evening and she kept telling me I was in her mind 24/7 that she couldn't see a future with him and wanted to be with me but just couldn't hurt him. She said she wanted us both but only wanted to be intimate with me.

If she didn't love me I could get over this but it is so hard when all she ever says is it's me she is in love and she loves him but is not in love with him. I feel broken as we could be so happy but can't continue like this. I am trying unsuccessfully to move on (blocking and then unblocking numbers) but can't get my head around why she just won't leave and be happy with me.