Here is another book suggestion perhaps more specifically geared towards what you asked for in your post.
I suggest you and your partner read “The body keeps score”
You don't. You bring your doubts, your worries, and your baggage. We all do, as people who are dating with past histories.
The relevant question is, "How do you keep it from impacting your new relationship?"
I'd suggest a series of:
Open and honest communication, especially when something scares you, even if you think it shouldn't.
Constantly reminding yourself that your friend is safe, your friend is not your abuser, and your friend understands.
Therapy, specifically a trauma-informed therapist, who can help you to process some of the damage from the past.
Setting solid boundaries, and enforcing them. The mental abuser played hell with your boundaries: your safety will some when you have established healthy boundaries and had them respected by your partner. Make it very clear to your partner how important the second part is.
Perhaps read Wendy Maltz's The Sexual Healing Journey - a Guide for Survivors with him, or read it and ask him to read it, too. There's a chapter for secondary survivors, but just understanding everything will be very eye-opening for him.
Also, keep in mind that the repeat exposure to trauma - mental and physical, over five years? - goes beyond PTSD in your reactions to it. It will have some deeper impact. You may get value out of reading Pete Walker's Complex PTSD - From Surviving to Thriving.
(Both links to amazon)
Last, be patient with yourself. Healing from this kind of situation is not a destination, where one day you will be 100%. It is a journey, a process, which you will overcome one step at a time. Patience and self-love are keys for you.
It can be so important for your boyfriend to have you as a resource for support. But, his assault affects you, too. Self-care is a necessary part of supporting a survivor.
It depends what you think will be most relaxing and helpful. Maybe you need a day off where you don't talk about the assault. Maybe you need to talk to your boyfriend on that day, but tell him he's not allowed to talk about the assault. Maybe you have to talk to a friend or parent about the assault and ask them for help. It could be helpful for you to see a therapist yourself. A bath, a night in watching a movie, or taking a walk around the park could be the way to relax.
You mentioned that your sex life is going to be gone for a long time. Is this something you've spoken to your boyfriend about? For instance, he might not be capable of sex, but he might be able to do other things for you. There's a book called The Sexual Healing Journey that could be a good resource for both of you.