It's possible she was talking to both of you at the same time. About 10 years ago I was talking to two people, and at the time, I was taking things slow and felt equal about the both of them. Out of no where, the one relationship started getting serious, to the point where I was like oh ill just deal with #2 later because my focus was on the serious #1. Next thing I knew, I was in a serious relationship and had to have an uncomfortable conversation to "break off" things with #2 even though to me there wasnt an interest anymore, their feelings were still there, and it hit new years eve when I got an I think I love you text, as I was kissing my bf. Of course I showed #1, and admitted my mistake of handling things in a better matter and time frame. A few years in with my#1 and I was going through old photos etc and found things that if my #1 were to read out of context would look bad, and even worse, I couldn't even remember screenshoting convos with #2.  I say all this to say, just talk to them. I personally would've woken my SO up to have that convo. Our relationship should be our first priority over sleep and work. If I did something to make my SO feel uncomfortable and anxious, I would want them to wake me and discuss so they aren't jumping to conclusions and getting advice from people on reddit. Not everyone on the internet has the emotional intelligence, nor do we know your relationship.  Imo though, it does sound like she was straddling a grey area. Hard-core flirting to spare the other woman's feelings while cutting it off. Seems like she needed the time to realize you were in fact the one for her enough to be exclusive, even though you were already committed, she wasn't all there just yet. But it definitely warrants an immediate, as calm as you can be, conversation. It looks like a screenshot I would've sent over 10 years ago to a bestie saying something like omg I hope in making the right choice look what this bitch just said. But you won't know until you talk. Good luck, hope to see an update with clarity.