I believe the worst one to suffer in the upcoming situation will be Dev. He was always made to believe by Ishwari that her happiness lies in his and she will always support him in all his decisions. So when he fell in love with Sona he had no second thoughts on what if Ishwari rejects her???
So when he will come to know of Ishwari's true colors, he will be shattered. On one side he realizes that his own mother whom he worshipped as a Goddess is so selfish that she cannot see her son's happiness and other side he has to break relations with Sona who has always loved her selflessly.
I feel so sorry for Dev. He will have no one to share his grief and pain. Everyone in the family had always some kind of expectation from him but it was only Sona who loved him immensely without any expectation. He will be have to live with this guilt of breaking this girl's heart, showing her dreams which he cannot fulfill now and filling her life with tears.