My 15 year old stepson has become unbearable to live with he swears,shouts and has no manners what can I do?

My 15 year old stepson moved in with my husband our daughter and I 18 months ago as he said he hated his mother and didnt want to see her again - she said he had become very difficult. He promised to improve his behaviour and learn to help in house a little and be able top do things for himself (was very molly coddled). Things were okay but recently he has become very close to his mother again (I'm pleased) but now his behaviour has become over time unbearable he shouts swears has no manners and says he hates both myself and husband. I am worried this is effecting my daughter who is 5 as she is trying to copy some of his behaviour. I feel I have lost control of the situation this has not been helped by my husband who has always taken a dim view of my previous firm parenting and sometimes did not support me when I feel we should have been diciplining him. He now recognises that his behaviour is out of order but I think too late.