Breast ultrasound image segmentation is a very challenging task due to the low contrast and blurred boundary between the breast mass and the background. Our goal is to utilize the powerful feature extraction capability of SAM and make out-of-domain tuning to help SAM distinguish breast masses from background. To this end, we propose a novel model called SFRecSAM, which inherits the model architecture of SAM but makes improvements to adapt to breast ultrasound image segmentation. First, we propose a spatial-frequency feature fusion module, which utilizes the fused spatial-frequency features to obtain a more comprehensive feature representation. This fusion feature is used to make up for the shortcomings of SAM's ViT image encoder in extracting low-level feature of masses. It complements the texture details and boundary structure information of masses to better segment targets in low contrast ultrasound images. Second, we propose a dual false corrector, which identifies and corrects false positive and false negative regions using uncertainty estimation, to further improve the segmentation accuracy. Extensive experiments demonstrate that the proposed method significantly outperforms state-of-the-art methods on two representative public breast ultrasound datasets: BUSI and UDIAT. Codes will be released upon publication.