Who is Elizabeth Proctor (and what does Abigail think of her)?

These characters are from a play called The Crucible by Arthur Miller. Elizabeth proctor is basically the wife of John proctor. She has three children with her husband and is currently pregnant with the fourth. To help her out, Elizabeth goes to employ Abigail as a servant. Abigail is the niece of Reverend Parris.

Now, Elizabeth found out that her husband is actually having an affair with Abagail behind her back. Meanwhile, Abigail doesn’t like Elizabeth at all either and is jealous of her. She wants to replace her as the mistress of the house and something bad will soon happen to Elizabeth.