<human>: We've been together 6 years. 

Over the past year she slowly got closer to this guy at work. Recently, right after she switched to a job at a different company, he kissed her at his apartment before a party. She backed off (she has sent me texts with him that prove this is exactly what she did), but admitted to me she thought about the kiss a lot, and did/does like him back. 

I made her pick between us, and after about 2 weeks, she chose to be with me and cut him off and stopped messaging him.

Recently, however, they ran into each other for the first time since the kiss at a mutual friend's party. She said the meeting was awkward, but admitted to messaging him after the fact saying it was nice seeing him. This infuriated me. 

Since then, she said he has crossed her mind, even though she's really happy with me and our relationship. She tells me she still has about a "5%" crush left, and has admitted to being "curious" about him (especially since he stopped messaging her), but that she doesn't want to lose me, etc. However, while she acts pretty normal in person, she is pretty distant when we're texting.

I feel like I'm being taken advantage of, and am currently at her mercy because I'm essentially just sitting around waiting for her to make a choice.

What is the rational/objective thing to do in this situation? I text her way more than she texts me at this point.

Could you distill the essence of the text into 1-3 sentences?
<bot>: Girlfriend of 6 years admits to having some feelings for someone else, but still tells me she loves me and wants to take my last name. Now I'm just stuck in the middle waiting for her to lean one way or another.