Apparently the song is about Kevin.
I agree with Michaela;x - In the song she used to want the guy to love her just as much as she loved him, but he never did which is a lot like Britney and Kevin's relationship ( well from what we know from "Britney: For the record" and "Chaotic").
The term "out from under" is obviously her emotional state. She was feeling depressed and in a dark place (under), and when she is "out from under" she claims that she will "figure it out" (such as her personal life and career, I'm assuming).
Apparently the song is about Kevin. I agree with Michaela;x - In the song she used to want the guy to love her just as much as she loved him, but he never did which is a lot like Britney and Kevin's relationship ( well from what we know from "Britney: For the record" and "Chaotic"). The term "out from under" is obviously her emotional state. She was feeling depressed and in a dark place (under), and when she is "out from under" she claims that she will "figure it out" (such as her personal life and career, I'm assuming).