This is section 13 - (1) Any marriage solemnized, whether before or after the commencement of the Act, may, on a petition presented by either the husband or the wife, be dissolved by a decree of divorce on the ground that the other party-
(i) has, after the solemnization of the marriage had voluntary s*xual intercourse with any person other than his or her spouse; or
(ia) has, after the solemnization of the marriage, treated the petitioner with cruelty; or
(ib) has deserted the petitioner for a continuous period of not less than two years immediately preceding the presentation of the petition;
As advised, u can file application for access to ur son in the same case of divorce filed by ur wife ...
without knowing the basic facts as to what occurred between u & ur wife, it would be difficult to help u about filing criminal cases.