I could not stand Ana Lucia either, terrible acting. I think seeing Libby was just a way to show us how absolutely racked with guilt Michael is. So we the audience would be more sympathetic to him. The music playing in Michael's car when he first tries to kill himself is Cass Elliot. When we first see inside the hatch we hear Cass Elliot singing "make your own kind of music". Another way to show he is haunted by his past.