It seems to me that the confusion really stems from the fact that YOU don't REALLY KNOW what you want in respect to your relationship with XW. What do you want to happen? Just a friendship? Or something more.
Man, you gotta lose that word 'manipulation' because it just makes you fear-ridden and causes you to act unnaturally. One it isn't fair to you, two to XW, or thirdly to the two of you. You might want to shift your perception from 'oh my gosh...I gotta avoid manipulation' to 'this is a precious gift of the moment and I will honor it'. See?
XW reached out to you and you can honor her grief by being present with her. Yeah, I can relate that the first phone call presents a host of challenges for both parties. Been there myself. Sometimes people get too hung up on 'how should I say this and that'...it just gets in the way of the process and the flow of the convos.
Please try to lose that fear of 'manipulation' and put the focus squarely on truly appreciating the gifts--small and large---that come your way.