Reason for Dugba's anger

Yes Dukba is angry on LNV for not marrying her and removibng all that anger on innocent Saras who may not even know of some issue like that. And the way she spews venom in her words and her eyes its lucky saras does not care that much else anyone other person would have blasted her by now

I agree, but how can she not see the goodness in saras? Can she not see that he still has his mothers good values and beliefs and not gumans as Guman said on the phone to dugba.

When she heard that Saras touches Ghuman's feet everyday and respects her, she could not accept it and pushed Saras also to the enemy camp.

Like I said before love is blind but hatred is blinder...

Some observations;

Dukhba (unhappy lady) is married but not showed widowed. As per book, her husband Sahasrai has gone abroad to try his luck and she is spending a semi abandoned wife's unhappy days under the shelter of her brother and SIL, that is VC- Guniyal. She has a daughter and now she is not interested in LN.

Some guess work as per serial;

Obviously LN appears to have had her rejected in favour of a 'Nachaniya', before she too married other man. This rejection came with a betrayal edge. For she appears to have taken care of Saras after Saraswati's suicide and some misleading encouragements from the LN family (' they ditch even a woman who took care of their son', she said.) Plus, Guman seems to have vitiated baby Saras against her. In that phone call from Dubai, he blows out and blurts to a misunderstood identity of his friend, that "he did not want to meet anyone, least of all the one Who had sent mother to pond. " These must have been Guman's patchwork. She was successful in keeping the fire stoked at both ends with some false conjectures...So yes, her anger was directed towards LN on the whole.

The other dialouge she said makes you actually wonder what must've happened back then? She says ," both father and son manage to gain your trust and then betray you."

This might point out to the problem actually. Its possible that LN might've given her false hopes and then went away and married Gumaan. Gumaan also hinted towards the same.