Welcome to SR and sorry for the reason that brings you here. In my opinion, you found the right place for guidance on this issue from people in similar situations. I know the first temptation is to figure out how to try and deal with them, how to help them, and how to fix the situation as soon as possible. I know the last realization is "how do I take care of myself." But try to take care of your needs. This is hard at first, and then with practice, it gets easier.
You will hear from so many wonderful people on this forum who have been to hell and back. I really recommend reading posts from others- both from an addicts perspective and from family and friends of addicts.
The bad news is that you are in a very volatile situation, which may be hard to recognize at this point. The good news is you have choices. I invite you to read my posts regarding my relationship with my AXBF (addict ex boyfriend) and you can see the ups and downs of life with addiction and the mental games we play with ourselves.
I feel lucky that I did not marry him or have children with him even though that is what I thought I wanted. I was just obsessed, infatuated, and equally addicted to him as he was to heroin. Finally, after years of chaos, I learned how to love myself which for me meant letting go. I am not saying that is the only option, but it's helps to get in touch with reality as soon as possible regarding your situation to avoid you going down with him and his addiction. Al-anon meetings, therapy, and SR are a few good resources. Also, read the stickies about this section.
Glad you have joined us and please keep posting. It really helps and saved me during desperate and painful times.