It's really hard to see what drugs does to a person. I think you are wise to see this is who he is now, it's not too likely he is going to change. However, that does not mean you cannot change. Don't look back, just the present, the here and now.
This is who he is, and this is the situation. What is within your control to change? You don't have to answer, it is just something to think of for yourself. Baby steps.
XXX