She is overplaying her hand because it has worked in past. She might have initially not like Anokhi because of Astha but now it is more than that. She has seen how strong Anokhi is and how much influence she has on Shaurya. If Shaurya were to marry her, the dynamics of Sab house would change. She will lose her iron control on the members of the household and all her past wrongdoings could potentially come to light. I also think somewhere in the back of her mind, she really believes she is doing Shaurya a favor- after all what could a middle class girl with shady family bring to marriage. In her mind this is tough love.
No one truly knows Shaurya, it has been shown many times. Almost everyone including BM believes that his love for BM trumps everything and he would be willing to do anything and everything for her. He is blind to everything when it comes to BM. Let us be honest, so far he has. But it is not just his love that binds him to BM but his feelings of gratitude and indebtedness too. I think they are about to be shocked.
Devi does have some weird definition of class. She's mentioned that Gayatri and Kanchan come from poorer families, but maybe they're not "middle-class" or from the village. All the insults that Shauyra used to direct at Anokhi, came from Devi. Some of that is tied in with middle class people having self-respect but also middle class people being gold diggers. Devi's got all the stereotypes.
Devi must really think she's saving her son to be willing to sacrifice her relationship with him.
I'm so glad they've shown Shaurya to be aware of what's going on around him. He is still being selective about when he reacts to the unfairness that he sees. I was impressed by his rant against the engagement. He knows he's being blackmailed. He knows it's all wrong. He gave in because he values his Badi ma over his own happiness, and willingly gave that sacrifice for all the years Devi committed to him!
I can't wait to see what he does now!