I would not mention anything about her actions. You are throwing fuel onto the fire and said yourself that she can become hostile very quickly. She may see a comment about her behaviour as a furthur dig at her. I would do one of two things. The first being, gather all of this childs belongings into a bag and then drop them at her door. This way she has no reason to contact you furthur and the back and forth will be over. Also include her tax reciept and then next year you don't have to be in touch with her again. The alternative would be to leave the bag of stuff on your front door step for them to collect but its whether or not they come as planned and the chasing up that may result. If it was me and I was able to I would take the stuff to her place, as then I am in control of how things will go more and I can have closure quicker and on my terms.