There could be a few reasons on why she decides to be sort of distant. I am thinking maybe she feels sort of worried or stressed out about your situation and there are certain ways that people act to try and "make things better". She probably sees you as somewhat as a stressor and her way of coping is maybe to not think about you. I would just give her and yourself a little room to breathe at the time. Hopefully everything just kind of gets better for you and her. Also, she could also be looking out for what's best for her kids. She might think that your behavior could influence the kids in the wrong way. I hope everything works out for you.