Wendy is a brave, courageous woman whose heroics help save her son, herself, and Dick Halloran. She suffers three broken ribs, a busted upper calf, a scraped ear, a "shattered vertebra" (58.5), and "internal injuries" (58.5) – all from Jack, the mallet, and the stairs where there battle occurs.
This is the first time Jack has physically abused Wendy that we know of. Remember this moment, when Wendy finds Jack in the ballroom drunk, just before she locks him in the pantry? Jack's come to and grabs her ankle. When she protests he says, "I'll hurt more than your ankle, you bitch" (46.67). We are told that, "The words stunned her so completely that she made no effort to move when he let go of her ankle […]" (46.68). Jack has spoken harshly to her before, but, even when drunk, hasn't really physically threatened her or called her names. That's why she's so shocked.
In the tradition of Sarah Connor, and Scream's Sidney Prescott, Wendy is also a special kind of horror woman because she survives. She keeps doing things that don't seem very smart – the kinds of things that can get a character killed. Some of her actions make the reader cringe in suspense. A prime example is the way she keeps going to check on Jack. Like Danny and Jack, Wendy is propelled by curiosity. Wendy's curiosity about Jack's state is part self preservation and part genuine concern for her husband.
Wendy is trying to balance staying alive, protecting her son, and trying not to utterly abandon her husband. Like Jack and Danny, Wendy thinks of the Overlook as their last chance for success as a family. But, when she sees what the hotel is doing to Jack and Danny, particularly Danny, she becomes much more pragmatic and comes up with some options. When they are indeed trapped, she knows things might come to violence, which is why she carries around the kitchen knife when things get grim.
Another thing that keeps Wendy from trying her very hardest to get out of the Overlook is her fear that she'll have to go and live with her mother. Wendy is afraid she won't survive the winter if she does that. We can't really blame her. Her unnamed mother sounds pretty gruesome and dysfunctional. It wouldn't be a good environment for Danny either. The boy is aware of all this, and it contributes to Danny's clinging to the hotel. Similarly, Danny's fear of DIVORCE and losing his beloved father impacts Wendy's early decision making processes.
What Saves Wendy from Redrum?
A few things seem to save Wendy from redrum (that is, MURDER – see "Symbols, Imagery, Allegory" for more on that), are some of them the very things that at first seem like they should kill her.
In Jack's section, we explore the possibility that he has similar abilities to Danny. Wendy, on the other hand, seems largely immune to the Overlook's evil. Does this mean she doesn't shine? She doesn't have dreams, visions, see hedge animals move, or see her inner demons take form, or any of the other things that happen to Jack and Danny. Basically, she hears some voices, some music, and she finds some party favors in the elevator.
The Overlook doesn't have much interest in messing with her mind, at least not directly. Then again, it does want her dead, though there's no hint it wants her because she can shine. Rather, her death is necessary to the Overlook's purpose of destroying families and perverting all that is good. Maybe the Overlook doesn't bother Wendy because she can't shine, meaning, she can't perceive what's going on in the hotel most of the time, so she can keep her wits about her in ways Jack can't.
Although she doesn't seem to have supernatural perception, her ability to believe in such things contributes to her survival. She is able to face reality, even when that reality is supernatural. Before the hideous battle with Jack, she comes to terms with the reality of Danny's ability, and the reality of the Overlook. She doesn't question or doubt the evil of the hotel. Up to when Jack begins chasing her with the mallet, Wendy's thoughts are often analytical and almost cool. She's keeps a running account of the facts of the situation in her head, like here:
(Don't push the facts away this time, girl. There are certain realities, as lunatic as this situation may be. One of them is that you are the only responsible person left in this grotesque pile. […]) (46.2).
She doesn't come up with any solutions in her musing, but she does see the truth, whether she shines or not. This ability to keep a solid grip on reality under the most extreme kind of pressure is the kind of things horror stories like to reward their characters for.