Cannot remember title of movie classic kung fu movie

by mario
(chicago)

ok so the plot goes... a sister and brother and another guy maybe adopted brother falls in love with the sister and gets sent away maybe because the brother got jealous. but then the brother becomes real protective of her and turns real crazy super villain and starts poisoning himself with all kinds of venomous insects and stuff and he becomes all pail and could kill people just by touching them and so on till the guy comes back and throw down and so on. please help me remember the name.