...the suppressed chapter published posthumously where Stavrogin confesses having raped a little girl?

Btw, I just found out the "official" academic edition of the novel (vol. 10 of the 30-volume complete works, published in 1974 in Leningrad, as it was known then, officially - unofficially it was still Piter) has about 510 pages for the novel proper, the additional chapter (printed in vol. 11) is another 25 pages.