Article continues below advertisementBritney Spears made a lengthy Instagram post as she continues to slam the shocking allegations ex-husband Kevin Federline made in his new memoir.On Sunday, October 19, the singer uploaded a photo that showed her riding a horse. The star was wearing a fedora hat and a shirt that put her back muscles on display.Article continues below advertisementBritney Spears Feels Like Someone Took Her 'Wings'Source: @britneyspears/instagramBritney Spears reflected on the 'traumatic experiences' she's endured over the years.