If someone finds Aarti's actions and words at the Mandir disrespectful and disgusting, then the concept of the show is lost on him/her.
Wasn't Yash standing right below, begging his wife for direction, while Aarti was begging Prashant for the same?
It was not meant as infidelity on her part. If anything, at that point in time, she felt she owed Prashant, not Yash. Both of them were doubting the marriage. Both of them were considering breaking it off, at the slightest sign from their beloveds. Its just that her past love still has a physical manifestation, whereas Yash's does not.
Yes, she could have acted with more tact, but she didn't. Aarti's characterization and her relationship history (and previous interactions with Prashant), made that scene what it was. If she had acted any other way, it wouldn't have been believable.
I lost no respect for her in that scene. I only sympathized with her. Hats off to production for making Aarti's weakness for Prashant (her image of him anyway), believable, despite the backdrop that is her strong, independent, single-mother character.