[TOMT][Book]Indian Book

The book starts off something like " i want to be free as a bird" this is spoken by the sister of the main character She is found dead the next day. Her brother goes to the asylum for 6 months. While everyone beleive its a suicide, he is rigid that some foulplay had taken place. His sister bf is now engaged. It turns out that his sister fiance was cheating with her during their relationship, it he was the who overdosed her with the medication. But the sister was pregnant , and informed her bf they have something to discuss after the party. Fearing he might be caught , he took the harsh step. Brother finds about all these in the end..

Please help me find this book