Yeah, I just need to take care of the email.
How's this for the email text:
"Hi [t's name], after last session, with the email and all of that, I started to feel really uncomfortable with how close you are to the situation, in that [abuser's name] used to see you for therapy, and I just feel too unsafe not distancing myself from him as much as I can. You have been very helpful, and it was very kind of you to see me without charge, but it's all too connected to my trauma, for me to feel comfortable continuing therapy with you. I still want to continue my healing, and you've given me a lot of tools that will help me with that, which I appreciate. I would like to cancel my future appointments, and I would like to try seeking therapy from someone who has absolutely nothing to do with the situation, and is completely removed from having anything at all to do with [abuser's name] in any way, shape or form. Thanks for all the help. -[my name]"