Britney Spears is back on social media! In case you missed it, the pop star deleted her Instagram account five days ago amid the controversy surrounding her ex-husband Kevin Federline's new memoir, You Thought You Knew. In it, the former backup dancer aired out a bunch of her alleged dirty laundry - including that she did cocaine while breastfeeding, punched their son Sean Preston in the face, wished their boys dead, watched them sleep with a knife in her hand, and more.