I resisted reading it because I vividly recall the day JFK was shot; I was just entering my teens. But my younger sister, who was a toddler in 1963, encouraged me to read it. I like King (despite his tendency to ramble and introduce extraneous people/plot lines), so I picked it up last year. I did enjoy it, and surprisingly it did have the negative emotional impact I feared. I got caught up in the characters he created, rather than the events of the day that served as the catalyst.
You should try to return books you “stole” from old friends, along with a note. You’ll feel better. For the library books, literature books, see if your local Friends of the Library can use them for their sales. Old textbooks, contact the schools if they’re still around. Tell them about the books and ask if they can use the books somehow (doubtful) and if you can make a donation to their scholarship funds. Any books that remain, count them, multiply by $5, and donate that amount to your local library, Head Start Program, etc.