Sentence:  She stood up , smoothing her hair down , straightening her clothes , feeling a thankfulness for the enveloping darkness outside , and , above everything else , for the absence of the need to answer , to respond , to be aware even of Stowey coming in or going out , and yet , now that she was beginning to cook , she glimpsed a future without him , a future alone like this , and the pain made her head <WSD>writhe</WSD> , and in a moment she found it hard to wait for Lucretia to come with her guests . 
Meaning of the word marked with <WSD> tags:  to move in a twisting or contorted motion, (especially when struggling)