I had some of the same qualms about leading on, about being confused, etc. My therapist dealt with it by making me realize that these were all doubts related to the future, not the moment I was living. As long as I don't lie to my dates and that I act on my true desires (i.e. not doing what I think others expect of me), I should feel confident that the future will sort itself out. And it does. Many of things that worried me about my dates fell into place neatly a few days or weeks later, when the time had come.
And I will second Vanilla in saying that your date is a grown woman who will think for herself. Continue to open up, acknowledge to yourself and to her the limitations of your feelings and engagement, without fear of her reaction. She'll be grateful for your honesty, even when it's not what she hoped to hear.
M39 D6 D3 (at S) S 2014-09 D 2016-09
"You can't start a fire sitting around, crying over a broken heart" - Bruce Springsteen.