Brendan McDermid/ReutersHuma Abedin writes in her forthcoming book that a U.S. senator sexually assaulted her in her 20s, kissing her unprompted and forcing his tongue in her mouth as the two conversed in his apartment.The longtime aide to Hillary Clinton, now 45, detailed the incident in her memoir Both/And: A Life in Many Words, set to be published next week, according to an excerpt obtained by the Guardian. Abedin withheld details of the senator’s identity, including his party affiliation, wh