The singer brought her fiancé, former MLB player Alex Rodriguez, on stage Friday to celebrate his 44th birthday -- with a cake and a song. In a video Lopez posted to her Instagram, the singer is seen her with her twins and Rodriguez's daughters wishing A-Rod happy birthday. "Celebrating you today and everyday my love... you are one of a kind, my hurricane and my calm in the middle of the storm...thank you for being such a beautiful light in my life...