Because of his affair with abigail williams, what does john proctor fear doing?

Answer: Expose her on trials.

Explanation:

John Proctor fears exposing Abigail Williams on court since he has no fehacient enough proof that could demonstrate that she is, in fact, a liar. There's the affair issue going around as well, he fears that this could come out at any part of the trial and of course, he wouldn't be trusted or worse, he could turn into a suspect.

he fears exposing her to the her as a liar due to his feelings for her, as well as tarnishing his own name.