Britney Spears is itching to put the pressure on ex-beau Justin Timberlake, former hubby Sam Asghari, her estranged dad, Jamie, and others she feels have wronged her in the past, according to sources. As for how she plans to do that, RadarOnline.com can reveal the pop star will reportedly bring the hammer down on her biggest enemies in an upcoming biopic based on her best-selling memoir. A source said: “They better brace themselves for major embarrassment because Britney isn’t going to hold back.” As RadarOnline.com previously reported, the Toxic singer, 42, recently announced her 2023 book, T…