Is a Divorce or Annulment Needed

My question involves divorce in the State of: California

I am engaged to be married, and we are living in Orange County, California. I married someone in April 2004 (in Las Vegas) without knowing that her divorce was not final. When we split up, I did not think to do anything with our marriage (i.e. divorce or annulment) because I thought our marriage wouldn't technically be legal since she was married at the time of our marriage. In order to make my marriage to my fiance legal, do I have to do anything with my prior void marriage, or can I marry my fiance without doing anything? Thank you for your help.

You need to divorce your wife before you can think of marrying your girlfriend. See, she can't be your fiance, because you already have a wife.