This person's confusion about their feelings for you and about what they want out of this relationship will gradually seep into you, to the point that, when it comes to each other, neither one of you will be certain which end is up. You'll fall for them, potentially very hard, but those strong feelings of need and desire won't be based on real life or the present so much as they will stem from your past-life bond with this person. They deceived you back then, perhaps even betrayed you, and created a seesaw of need and distrust that hasn't yet been resolved between you.
But there's no time like the present, as they say; and if you two are to establish an intimate connection in this lifetime, you'll have to resolve the uncertainty once and for all. For starters, you should try to remember that your strongly devoted feelings for them may not be a reflection of current reality. Take a wait-and-see attitude when it comes to declaring your passion or committing to this person long-term. It may take them some time to decide where they want the relationship to go, and it's up to you whether you'll wait patiently for their feelings to grow stronger, or simply move on.