Gong Jak Lai Dok Bua

Prom runs away with his rich girlfriend. After awhile he becomes a drunk while his wife is very ill. She eventually dies and Prom promises to establish a good life for his son so he lets the monk take care of him until he is stable. 20 years or so later, his son Pariwat is bullied for his status and such and Prom becomes rich involving drug dealing. Prom and his boss's wife are having an affair and the wife is crazy about him. Prom finds out Pariwat is his son and is always out to protect him but never tells him who he truly is.
(Source: AsianFuse Wiki)