Elizabeth's reaction to the affair reveals a bit of a vindictive streak. When she discovered her husband's sin, she gave Abby the boot and then proceeded to drop a few hints around town that the girl may just be tainted. (Isn't John a little responsible, too?)
For the most part, though, Elizabeth is a stand-up woman. Throughout the play, she seems to be struggling to forgive her husband and let go of her anger. And, of course, her hatred of Abigail is understandable. Elizabeth's dislike of Abigail seems justified later on in the play when Abigail tries to murder Elizabeth by framing her for witchcraft.
Overall, Elizabeth is a blameless victim. The only sin we see her commit is when she lies in court, saying that John and Abigail's affair never happened. This is supposedly the only time she's ever lied in her life. Unfortunately, it's really bad timing. Though she lies in an attempt to protect her husband, it actually ends up damning him.
After she’s spent a few months alone in prison, Elizabeth comes to her own realization: she was a cold wife, and it was because she didn’t love herself that she was unable to receive her husband’s love. She comes to believe that it is her coldness that led to his affair with Abigail. This realization helps Elizabeth forgive her husband, and relinquishing her anger seems to bring her a measure of personal peace. Elizabeth's noblest act comes in the end when she helps the tortured John Proctor forgive himself just before his death.