Sister has run having an affair with different caste man

Muhe meri behen ke bhare me pata chala ki uska affair hai koi different caste ladkey se aur voh ladka ki shadhi hogai hai in 2007 aur meri behen ne usey approach kiya 2010 aur jab se uska affair chalu hai , yeh sab mene ghar me bataya hum sab ghar waley ne usey smajaye 6 se 8 ghantae tak ki yeh sab sahi nhi hai itni sab baat honey ke baad hum sab ne decide kiya ki hum uskey ghar pe jaakey uski wife ko batayengey aur usey bhi bhol degey abb se milna mat yeh sab hum ne decide kiya sabkey sath aur hume laga ki meri sister smaj gayi par voh next day hi ghar se bhaag gayi kuch paisey leke aur kapdey aur voh ladka bhi uski wife se jagda kar ke bhag gaya aur dono ka number band ara hai ab problem yeh hai ki hum legally kya karey we don't want ki hum sabkey relative me naah ho aur humlog rent pe rehtey hai aur plus humlog ke pass agreement nhi hai rent ka agar humlog ne police me kuch kiya toh humlog ko ghar ke pass police nhi chaiyeh nd humare rent ke owner humey nikal dega aur abhi hum kidar nhi jaah saktey becouse of financial condition agar hum koi bhi complaint kartey humey bas yeh nhi chaiyeh ki owner ko police puchey aur ghar ke pass police nhi ayye plz help me