Sarah Ferguson spent last summer recovering from a mastectomy, and now the Duchess of York is dealing with another cancer diagnosis. Although the news was a surprise to fans, sources close to the ex-royal claim she’s remaining upbeat. “She is simply amazing, always looking for the positive in any situation and rarely thinking of herself,” the insider told an outlet. Ferguson’s loved ones continue to rally around her and believe she will approach her melanoma battle gracefully. “She is going to beat this disease, just like she faced down her breast cancer diagnosis, with bravery and good humor …