I don't think she's right but I do understand what's lead her to act this way. I personally sympathize with both of them. They're both in pain. They're both hurt. Neither of them are happy in their lives. It's not Sid's fault but its also not entirely Roshini's fault. The circumstances and everything that's happened has a role to play as well.
I've been where both of them are, not in the exact same way of course, but I understand. The loss of someone you love changes you in a way you never thought was possible and makes you do things you never thought you'd do. Sometimes you think you're doing the noble thing but you're not.
(AGAIN I'm not saying she's not wrong because she is. I'm just saying she isn't undeserving of empathy.)