Can Anyone Tell Me What Film This Could Be?

[caraamora]

The Film is british i think its from the 1980-1990's its bases around a teenage boy his sister and their drunk mother, there is a scene when he is in an alley and he see's his mother having sex with a fat man in a suit, and later on he and his sister are at home and his mother brings back two men and he threatens to kill one of them or something like that plz help me and my friends have been arguing about this for the last 3 nights