Gasp! I have that same book sitting here in front of me right now, Malaul.
I've been studying it - looking for weak spots and suggest you do the same. Take his book.....hide it and read it in secret.
I also suggest you watch the BF carefully......watch him from the corners of your eyes, so he doesn't notice. Move your stash of fresh body parts out of the frige and wipe the graveyard mud from your feet before entering the house, etc. Hyper-vigilance is the key word.
If all else fails......well you are an assassin, dear one, and wouldn't he be a lovely source of fresh parts?