I think it's important that she reads more up on polyamory more too. Some of what the people here are saying it's true. She has very bad way of wording herself with the whole deal breaker thing. Emotions are not a faucet, (and the usual familiar phrase can be applied to all emotions I think) you can't just turn them off, she needs to understand that.
It is important that you research your emotions, really figure out what your heart is telling you. Thats obvious and I think you understand that already from the little bit that you are saying.
She however needs to be responsible for her end of you two's relationship, with only what you have said, it seems like she's only worried about her emotions. Acting like if she is the only one who is going through a rough time. YOu have agreed and continue to agree to be open to her polyamory, thus you are meeting her needs. She should be willing to meet yours too, and that includes her researching and being able to provide ample communication that you are trully not going anywhere in her heart. Relationships take work, she just can't say "This is a deal breaker" after a little bit of expressed discomfort from your end, thats just lazy and irresponsible. You did your part, she needs to do hers. Maybe I'm just being harsh though. :/