No, not at all. Her decision to marry samrat would have changed only in one situation, i.e., virat marrying her in the same mandap. Otherwise, come what may she would have married Samrat.. now she has covered it under the "bhankas vaada" and if the vaada wasn't there she'd marry for the revengeful nature as you said. Pakhi is definitely self centered and egoistic and I'd like to add, over sensitive. The reason that I feel is that being the only daughter of an apparently rich "shahnav kul" family she has got every wish of hers good or bad fulfilled without any effort or problem, so even if the smallest of things don't go her way she takes it on her ego.. that is what she did by immediately accepting to get married to samrat when she thought virat had left her.
I also feel that she herself has a very low self esteem, that's why maybe she feels everything to be an offence (beizzati) against her. I know she calls everything that sai says to be beizzati coz she just wants to demean her in front of virat. But her lack of self esteem is a bigger reason for that. I don't know if she was like this before but maybe she is loosing her self worth in front of her own self coz she can see someone else taking a more important place in virat's life.
I just fail to understand why her parents don't make any efforts to put some sense into the girl.. just because she doesn't want to listen to anything unpleasant and against her whims and fancies and they don't want to upset her?! Then I'd say that more than her, her parents are responsible for her delusional state, for making her so over sensitive and doing only what she pleases.
@bold - I agree that Pakhi has very low self-esteem. And understandably, it is coming from her indulgent parents. I've heard that poor self-esteem is a result of not only over-critical parents but also over-indulgent parents who don't correct their child when required. Pakhi seems to have had that kind of upbringing.