There's someone in my head but is not me.

People always told me be careful of what you do And don't go around breaking young girls' hearts And mother always told me be careful of who you love And be careful of what you do 'cause the lie becomes the truth Billie Jean is not my lover She's just a girl who claims that I am the one But the kid is not my son She says I am the one, but the kid is not my son.