When the pain of being tired and abused is worse than the pain of staying with them - that is when you will leave. I was addicted to my addict just like my addict was addicted to drugs. I had to get help for myself to recover from my addiction to him.
I had to accept that I couldn't fix him. I couldn't stop him from using drugs. I am not that powerful. Therefore I focused on fixing myself in order to protect my child. Things are much better now. I feel sane again.
The information and support of the people on this site will help. Also, maybe try alanon or naranon or another support group.