I think Jon rejecting her showed her that she was never going to be loved and revered the way she hoped and that fear was the only way she could win. After all if the last male in her bloodline and man who gave up his crown could no longer embrace her.... who will?
Sansa tried to screw her. Her advisor Varys plotted against her. Tyrion basically enables the situation and now she knows he has serious doubts. The people won’t kneel to her willingly. She’s viewed as a foreign invader. Now her lover and the person she really should have ended up marrying is pulling away. She’s losing her children trying to help the realm, she’s losing her loyal army and best friends.