shabana bibi , 25 , from the muzaffargarh district of the country , died in hospital on saturday after suffering burns to 80 per cent of her body .
police have arrested her husband muhammad siddique and father-in-law pir bakhsh .
bibi 's brother , muhammad azam said siddique became enraged on learning his wife had visited her sister without permission - said he will set himself alight if he does not get justice .