how to ask husband 2 separate?
If you are in danger, you need no excuse to leave without a word. Do you have a safe place to go to?
He needs to get off the drugs and alcohol if there is any chance of having a functional family. He may get violent if you say you wish to leave, but if you are sure he wouldn't do this, you can tell him firmly that you do not feel adequately cared for in his home environment and that you are finding somewhere else to stay until he gets his mind, body and attitude in order.