Much like in the Ritwick phase, Dev is saying the things he really means to Sona but with a tone intended to imply that she has no idea what she is doing. When he said she was good as a nutritionist, it made me wonder about her journey into business world. The way I remember her, Sona loved being a nutritionist and having that one on one contact with her patients. She thought of this business for Saurabh's sake, so he could do the kind of work he enjoyed and not disappoint their parents at the same time. After the whole investment fiasco, it became even more important for her to succeed so she could become "equal" with Dev.
...and that is precisely where she is missing the whole point. The accusation that Dev never thought she could do anything was not completely true. He did many, many other things wrong, but not believing in her professional capabilities was never one of them. I mean, he invested 5 crores in her startup because he believed in it. Of course, all that has been understandably twisted by the words he let fly out of his mouth at their last meeting before the split... that she could never make enough money feeding people ghaas-pus. But it's not his "male ego" that is stung by her victory. Sona wants to make this a story about how she rose out of oppression, with Dev and the Dixits as villains, but in all reality, it's merely a story of broken hearts.
Dev isn't hurt by the fact that she is as wealthy and successful as him, or that she did all of this without him. He is hurt when she says she doesn't need him, period. Sona didn't know her power over him when they were married, and she still has no idea. It still kills Dev to hear that she is better off without him. And she does such a convincing job of portraying an unshaken facade (offense is the best defense) that he actually believes she isn't as affected as him... and then he goes further and further to get a reaction. Hopefully, this will eventually end in a conversation like the one they had in his office after the date with Ritwick.
On the other hand, after some cooling down time, I am glad that Sona got her bitterness out there. Dev literally had to break her wall down to get her to react, but they had to start somewhere. Dev is always caught off guard by the level of pain that this new Sona is willing and able to inflict on him. Her indifference bothers him, but her hatred and disgust is what really hurts him.