UFT President Mike Mulgrew was caught “in flagrante delicto” with a guidance counselor at William Grady HS, where he taught before becoming the union’s boss, a bombshell lawsuit charges. The accusation that Mulgrew was seen having sex with a co-worker in a woodshop at the vocational school, and that it was hushed up, comes in a rambling 73-page suit filed in Brooklyn federal court last week by Andrew Ostrowsky, a math teacher at Frank Sinatra HS of the Arts in Manhattan. Ostrowsky, 35, names Mayor Bloomberg, Schools Chancellor Dennis Walcott, Mulgrew and the UFT, claiming the teachers union conspired with...