Because of you - Kelly Clarkson, what are the lyrics about? I don't understand what happened?

She talks about her childhood and how her moms suffering affected her in her love life and to trust anyone in general. Her dad left when she was little too. Now in her adult hood she feels like the past is still there and affects her actions everyday. So she doesnt want to live like her mother did, unhappy and always crying. Thats why in the end of the video her and the husband make up.