I totally agree with you..I also think that Shiv would be the one to tell her the truth. I'd want him to. At the moment, he's the only one who could bring the truth to her..Nikhila and Mahen have tried to push Shashank and Devika out of the way for fear that they would reveal the truth but they would never even think of bringing harm to their son..So, Shiv is the only one who could reveal the truth to Gauri..And he would..