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You may not like the answer, but the best practice here is to listen to your instincts that tell you to stop this relationship. She is far from ready for a relationship and is still in major emotional conflict. (She is contemplating if she can love two people simultaneously and is "worried about this going to far". Neither is a good sign.) The emotions of your situation are driving her to not want to stop, true, but the simple truth is that she is not ready to make a choice.
You, and she, are at serious risk of being hurt. I know you have strong feelings for her; but the best recourse is to set some defined boundaries. If she decides to leave her husband, then you have a definite answer and can consider pursuing her. But, as it is....this is dangerous and will most likely lead to much emotional pain and trauma.
If you love her, wait on her, She is just not ready to make this level of decision. She may in time, but she needs space to think it through.