Monica Lewinsky did nothing illegal. It is not against the law to give anyone a blow job, at least for free.
The worst thing that could have happened would be that she would be banished from the White House. The Clintons certainly had no motive for denouncing her for anything. They certainly would have preferred her to just go away rather than to have any sort of fuss made about this.
As I said, everyone, always, should clam up and ask for a lawyer from the first mention that they could be prosecuted for anything.