child support and adultery.. please badly need your help

my brother is a OFW.. habang nandun po siya sa saudi his wife have an affair.. meron po kami pictures of evidence galing sa asawa mismo ng lalake na ka affair ng hipag ko.. confirmation and admission ng mother ng hipag ko at ng sister niya na my iba na siyang kinakasama.. ang problema kahit my evidence po kmi the wife keep on denaying the affair kahit na inaaway na siya online publicly ng mga asawa ng ka affair niya. tapos ang masakit na parte po my brother ang income nia sa saudi is only 18k a month he is working 12 hours a day lahat un pinapadala niya sa asawa at anak nia kahit na niloko pa siya pero his wife nabalitaan namin is using illegal drug confirm by her friends and mother. ang lakas pa ng loob mang black mail at mang gulo sa social media siya raw agrabyado at idedemanda pa niya kapatid ko dahil di sapat yung perang pinapadala.. please po help us badly need your legal advice..

Ms. Castmendoza ramdam q ang kapatid mo, halos parehas kame ng situation.. actually wife q p matapang at gs2 n nyang mamatay aq, d q maimagine n gnun ung gs2 mngyari ng wife q.. Nagpapakatatag lng me bcoz i have 2 kids, nakakaawa kasi n pti mga anak q niloloko ng wife q..

Atty. please give me a best evidence to file a case for adultery to my wife...