I'm not even as hurt as I thought I would be.
This might be a bit of a shocked delay in you being able to feel hurt by it. So of how when you hurt yourself, sometimes the nerves take a while to transmit the pain, your mind can block things form you that you aren't in a place to feel, as a form of protection. So don't be surprised if in a few days you are doing something mundane and THEN you feel the hurt, anger and betrayal of this. I've had delayed reactions like this, which seem to kit when I am tired, or about to get sick, and my defenses drop. OR, after I've been working on dealing with my emotions instead of shutting them away.
If you are not together then she could be sleeping with someone else...maybe she wants to see if things work out with this other guy first.
This is a sucky place to be, wondering if you are "back-up SO".
I was here for a while when BF was in his emotional affair stage, and when I was doing my best to ignore how much I hated it. I told him I needed to be not just #1 girlfriend, but the ONLY girlfriend, that I was NOT into being the consolation prize when the new(est) girl dumped him as a 'friend' after seeing his first rage. We made it through that and it started a lot of work on improving both of u, but we also had 12 years invested into the r/s by then. I really have to say for people with less time and emotional investment in their r/s, going NC and moving on is not the worst thing you can do, but only you can say if it's the best.
One thing - the minute you pull away for good, she WILL try very hard to 'win' you back. So if you feel that ending things is best, be prepared before that happens.