He is behaving like a complete and utter bastard. I think you should tell him calmly and firmly, that if he is still living in the house, he still has to take care of his domestic responsibilites, and since he is not, you would like him to move to his mothers immediately.
And that if he is too scared to tell his mother what has happened, you will gladly do it for him. It can't be worse than the horrible business with your dad, can it?
In any case, he needs to tell his Mum v soon - she may bump into your mum, or H's friend, or anything!!
Oh, LW, you don't need this. Bloody man!
But just think....you have set the clock ticking. This is exactly why your relationship has come to an end....and however slow, the end, and your freedom, is on it's way.
XXXXXXXX