I don't feel that Anika's character is butchered yet, omitting certain trp dialogues . She was like this only. She had been a strong person and all. But wasn't revengeful. She used to just tease Shivaay, after she got in OM after the rainy cheque receival. She never wanted to punish him neither was she angry. It was just on some high points she got upset and chose to ignore him.
Then just like Anika kept on pulling out Shivaay off trouble he has also done it several times. Unknowingly its him, that she calls up when she is in danger. Anika is not what she seems, nobody knows about her past, not even Shivaay. Although Anika puts on a bold mask, she does have a lot of insecurities. So just like Shivaay gets restless when Anika doesn't talk to him, his absence might haunt and pain her very much. This defines that breakdown scene, her fear to lose him, and to go back to loneliness. Its even possible that Anika's unbalanced psychological conditions may also be a part of her devotion to Shivaay, she does somewhat have a mild case of ptsd from her past.
(So somebody said that she is suffering from Stockholm syndrome... but that's actually wrong coz it is only if the victim and tormenter don't know each other prior to kidnap or something and still chooses to identify and feel for him)