Nobody forced him and he said he put it out there as a full disclosure. Sounds to me that he put it in to soften the blow of a current/future sex scandal.
I'm pretty sure I remember him saying something to that effect, that he has to do it to take the wind out of some potential blackmail. Which means there is potentially something worse about him than anything in his book, which fits with the JC meeting where he was hiding something from the whole story (why he turned the camera off / didn't record it).
Anytime he admits or confesses something I am sure it's not the full complete truth. So when he said "I'm going to have to say every 2-3 months for 3-4 years" about his visiting prostitutes, it could well be every month or few weeks for 5+ years. Not really a stretch.
It's like when your doctor asks how much alcohol you drink, and you say "I'm going to have to say about 2-3 a week" when you really know it's 8-9 ... bottles, LOL.