You can file petition for Divorce after 1 year of marriage. if its mutual then you can file any time still it will be dragged beyond a year.
read about Divorce and other issues here http://mynation.net/sm/ as per your religion
Whatever her or your past and any such issues you have to settle out before your marriage, now crying over split milk is not use and no one will listen, even if you have proof of her past encounters now you cannt do anything and useless.
if she still keep in touch with old flames then only you can sue her with adultry in divorce.
As she left you, and you do not have any false case aginst you so far then report it to police, get copy of your report dully signed by police, let her tell police that she left her own; else if she approch police before that you abandon her/kicked her out then you will be in trouble.
update us farther development if any.