Who's The Liar?

So we are watching our liar in chief accuse his former National Security Advisor of lying. One is know for lying almost constantly and often quite badly. The other has a reputation of being outspoken and somewhat controversial but has never been accuse of lying. So the liar doesn't like the tell all book the second in publishing and accuses the second of lying. Who would believe that. Books need to include interesting things in order to sell. The details revealed in the book are clearly reasonably accurate recollections. The opinions and conclusions are those of the author so everyone is free to draw their own. However we already know who the liar is.