^^^^^^^^^
I agree w/ the above. In fact, Jyoti does fine when only Badima is around, and was doing quite well during that time, aside from Sudha's arrest (here, Uday & Pankaj were there for her) and the hadsa. In fact, let's face it - CM is actually Pankaj's Kaki, and he has no reason to give her more importance than she's worth. Granted, she has a special relationship w/ him, but given how uncomfortable she makes his wife, he ought to recuse her from serving him. In fact, I hate how Pankaj tries to see the positive in CM when Jyoti complained to him about her.
It is more saas-bahu like for Sudha - here, CM is her own saas, but despite that, Uday was all set to walk out on her, until Jyoti interfered and spoiled things, talking of CM's right to reject Sudha. Says f**king who??? They've gotten married legitimately in a temple, their marriage is recognized by society, and CM herself 'conceded' defeat in trying to contrive Uday's return. Either she honor her terms of surrender, or let Uday leave. Jyoti's ridiculous demand that Uday let Sudha fight her own battles, especially given her condition, is insane, particularly given how Jyoti is incapble of fighting her own battles. In fact, Sudha's biggest enemy here seems to be her own didi, rather than either her own saas or own didi-in-law.
About CM, you are right, and there is absolutely ZERO character consistency b/w the CM of old (before Jyoti's marriage) and CM now. When CM first met Sudha in a marketplace as the latter was chasing her to return her credit card, she admired her on her honesty and remarked to Uday later on, when he was sulking over Devika, that she (Sudha) would be quite a good wife for him. At that time, she didn't seem to think about Sudha's background - just the fact that she was a sweet honest girl seemed enough. And like you say, CM admired Devika, welcomed her into the house and everything, and once drew parallels b/w Devika's and her own assertiveness. Her dislike for Sudha started after Pankaj had to cut short his honeymoon (but that wasn't Sudha's fault, and even Jyoti didn't want it cut), and when she perceived that Sudha was encroaching Devika's love life.
However, what did contribute to eroding CM's liking for the Sharmas was more of Jyoti's escapades on Sushma, which she to this day doesn't know about. Also, Jyoti's working in one of their charities to send money home also rubbed her the wrong way, but Pankaj ought to have told her that that was one of the marriage conditions w/ Jyoti that he had agreed to.
At any rate, Jyoti often running off to her maakya to resolve either Sushma's or Sudha's problems was the root of all this. I'm glad that at this point, Deepu has decided to handle it himself, and hope that it stays that way and that he doesn't escalate it to Jyoti. If Deepu manages to find Sushma, she should also tell her that she'll be causing Jyoti more trouble if Jyoti has to come out to get her home.