Sorry if you’ve already clarified this but, in your opinion, how much responsibility does Sansa have for Ned’s fall and the success of Cersei’s counter coup? Cersei makes a big deal of Sansa spilling everything to her, but is that true or is it just Cersei trying to give herself credit for how ‘well’ she’s been doing keeping things together? It definitely leaves an impression on Tyrion in the later books.

I covered this here. 

1. Sansa didn’t inform Cersei of the existence of Ned’s counter-coup, Ned did that himself. 

2. Sansa didn’t allow Cersei to foil Ned’s counter-coup. LF did that.

3. Sansa may have contributed to her own capture, because the only things she could have shared with Cersei were the precise timing of Ned’s coup and the fact that he planned to put them on board ship.

Cersei makes a big deal about it to Tyrion because it’s the one thing she can take credit for besides Robert’s death.