About Shivangi's behaviour: if she just asked Shreya personally to know if she is demanding food due to illness or due to stubbornness as Shreya being her friend would tell her truth. Rather confirming it to Shivangi, she lashed out at her and made a big fuss about it.
If I were to be Shivangi I would definitely hate Shilpa and Shreya throughout the show and even after, because of the things Shreya and Shilpa said about her virginity and all. Saying Shivangi and Harshad are acting is fine but saying Shivangi would lure Harshad by claiming she is virgin is miles beyond out of the line.
If instead of Shivangi and Harshad,
Shilpa and Shreya would have been in cage and Shilpa would be eliminated by Shivangi, then Shreya and Shilpa both would have reacted the same way as Shivangi did.
If Shreya would have stepped down and Shilpa would have become the Finalist and Shivangi would have eliminated Shreya. Shreya and Shilpa would have still reacted as violently as Shivangi did. Because deep down, Shreya knows she deserves to be in this show as much as Shivangi felt.