Yes I thought he was being a bit careful because he knows that you are talking therapy and beginning to put up a few boundaries. He is concerned that your therapist will identify what he believes you dont, and the risk to him is exceedingly high if you did call the police.
You have threads and threads here of expressing whats been going on, as well as your friend, and you have therapy and proof of speaking to WA. There is definately a picture here building up which would be more than 'he said/she said' if things ever progressed. It was one of the reasons why a GP visit was suggested, especially after the soreness.
You are actually getting to be in a powerful position, even if you dont realise it. Not that you are going to threaten him with the police, because that would be, I believe, life threateningly dangerous for you, but once you are away, its a useful dossier of evidence you can use to, for example, keep him away from you and allow you the space to recover. There is, as far as Im aware, no timeline on historic abuse. So maybe you could go to the Dr and add another bit of your safety net