1) you cannot convert to islam for purpose of remarriage
2) SC has held if a Hindu despite his Hindu wife, converts to Islam, and contracts a second marriage, his first marriage shall subsist and the second marriage shall be illegal and he shall be liable to be prosecuted and punished under section 17 of the Hindu Marriage Act and under Section 494 of the Indian Panel Code which prohibit second marriage during the subsistence of the first marriage.
3) Conversion does not end the first marriage but becomes a groused for divorce, and unless the first marriage is dissolved by a judicial verdict, no second marriage is permissible under any other Personal Law and if such a second marriage takes place the same shall be void and the person may be held criminally liable for a bigamous marriage.