Last week, Shar Jackson told Usmagazine.com that contrary to reports, she is not pregnant with ex Kevin Federline's baby. Today, she wants to prove it. Jackson, 29, confirms that she has hired attorney George Gallegos and is looking to sue Star Magazine for starting the pregnancy rumor. The Ex-Wives Club star exclusively tells Us: "I just got a little tired of selling magazines for Star and not even getting the respect of them telling the truth." And Jackson tells Us she is willing to put her money where her mouth is, volunteering to take a pregnancy test to prove her case. "I have extended a pretty good offer, since they are 'standing by their story,' by offering to prove them wrong and yet they have not responded." Jackson says she just wants the truth to be acknowledged. "These sorts of lies can damage my career, my relationships and are confusing for my children. This is about principle, not money."