Suggest Treatment For Depression

sir, i am in lot of depression due to my wife cheating. i had a sex with my wife two days before her monthly date. normally it takes five days. because of my official work i have to go out for four days. after ten days i saw on undergarment of my wife there is scattered sperm. but till now i have not asked any question. even though i have not made any physically relation with her. married woman the mother of one baby with out intercourse.does sperm flowback from vagina automatically without sex. if yes then no problem. if no then i wife has cheated me. Dr. revert back with detailed please.