Your second marriage is void under Section 11 of the Hindu Marriage Act 1955 (HMA) because your first marriage was subsisting at the time of solemnisation of second marriage. Section 5 HMA explicitly makes that no spouse of the first marriage should be alive at the time of solemnisation of the second marriage.
Your second marriage has been declared by the competent court null and void. It proves that you have committed bigamy. You are a guilty party hence, you cannot seek divorce on your own fault. If your wife agrees to get separated from you then you should convince her to file divorce case.
In the current scenario you cannot invoke Section 13 of the Hindu Marriage Act for divorce.