Another way of looking at it could be to ask yourself the question:
'What would I need in order to feel comfortable about going ahead with this situation?'
As in, you rightly say J is being too pushy, which implies you're not comfortable enough yet. That also implies you may be comfortable enough at some point in the future.
So what would need to happen between now and then in order to bridge the gap? What is not happening now that is causing you to want to push back?