I don't know about any books, but I can share my experience, maybe you'll find it helpful. When my life collapsed a couple of months ago, I was devastated, I thought I couldn't take it anymore, and CTB was the only way out. This led me to thinking I NEED to do it, I set deadlines, planned dates. Obviously, I'm still here to write about it. With time, I learned a valuable lesson, that when you're driven by strong emotions, this won't work. Right now I noticed, that something changed in me. I no longer struggle with life. I've given up. In social interactions, at work or with friends or relatives, I feel like a ghost, like I no longer belong to this world. And I made peace with it. It's not despair that's driving my decision at this point, it's a conscious, thought through choice. And when I go, it will just be a formality, because my life has already ended. A wonderful life it was and I'm grateful I could have it. But it's over, and last month was for me a journey which lead me to fully recognize this fact.
You know what helped me? It wasn't reading, it was writing. Putting on paper everything that went through my mind (related to the CTB decision). Returning to those texts after days and weeks. Reading them. Thinking about where I was wrong, what made sense, what didn't. Writing new texts, and reading them several times. Over and over. Until finally, I'm no longer rushing, I'm no longer desperate. I managed to detach myself from this world and CTB no longer seems to me like a violent act but rather a way of taking care of myself. I've seen death up-close. I held a dying person's hand when they passed. This changed me. But it didn't traumatize me, quite the opposite. I'm no longer afraid of death. The peace and relief I've seen in them when it happened. It almost made me envious at that point. And I think to myself, if that's what death is like, then there's nothing bad about it. Luckily, I've lost my reasons for living, so there's nothing keeping me from doing it myself.