Because she was trying to protect all three of them. She was prepared to cover for Zoe before she even touched Den.
Without a car or mode of transport where else was she meant to take the body?
Because she's trying to cover their backs. It's not just pressure from herself she's got..she's covering for two other woman at the same time too.
Does this look like a woman who planned to murder her husband? Who has no remorse for her actions?
http://img.photobucket.com/albums/v2...nart/IAM11.bmp
She's tied to the Vic now. It's her insurance to stay in Walford because she can't leave him behind. She can't just pack up and go because as soon as she's gone if they find the body that's it. Games up and she's, Sam and Zoe are in prison.