Prince Harry claims he had enough material for "two books", and did not include some things in his memoir because his father and brother would never forgive him.
He told the Daily Telegraph there were some things he just does not want the world to know.
He also said he wanted an apology to Meghan from his family members.
Spare, published this week, has become the fastest-selling non-fiction book ever in the UK.
The book outlines a long list of grievances against the Royal Family, as well as unresolved trauma over the death of his mother, his struggles with mental health, the isolated life he led before meeting Meghan, and the breakdown of relations with family members.
Kensington Palace and Buckingham Palace have both said they will not comment on its contents.
