Valentine's Day and celebs are getting into the spirit of the heartfelt holiday.From touching Twitter posts to infatuated Instagram messages, here are some of the wonderful ways celebs are sweetly sharing their love on social media this year.Barack Obama delighted fans when he took to Instagram to show his love and appreciation for wife Michelle Obama and their two daughters, Malia and Sasha, with a sweet message and a beaming family portrait.«Happy Valentine’s Day to the three who never fail to