The speaker imagines her closets as haunted, crowded with ghosts. Some guard sentimental keepsakes: dolls, letters, old books. Others hold the things she never did, never made, never had, including people she might have loved. At first the ghosts seem gentle, even tender, and they look like her mother, her dead sister, the men who almost stayed. That makes them hard to send away.
Then the speaker turns on them. She decides they aren't really the past at all, but fear of remembering wrongly and fear of loss still to come. They corrupt what she has lived and weigh down what is ahead with regret. So she screams, stamps her feet and waves a broom, and they shrink away like moths.
The mood moves from wistful and dusty to tense, then to a firm, almost comic release. The ending is calm and plain: the future is just the future, and her belongings are only things.