Sentence:  But you must remember that we were boys together, and a fellow naturally confides in a chap he was boys<!--"boys":sic--> together with. Anyway, be that as it may, he poured out his soul to me, and he hadn't been pouring long before I was able to see that he was <WSD>cut to the quick</WSD>. His blood pressure was high, his eye rolled in what they call a fine frenzy, and he was death-where-is-thy-sting-ing like nobody's business. 
Meaning of the word marked with <WSD> tags:  To hurt a person deeply, especially emotionally.