hi hopeandpray and WELCOME to SR! This is a wonderful place filled with supportive and humourous people. I'm glad you found us.
I don't know if you're aware of the 3 C's of addiction, so I'll post them just in case:
You didn't CAUSE it.
You can't CURE it.
You can't CONTROL it.
Regarding your situation, I'm sorry to say that no matter what you do, say, think or feel, you have absolutely no control over what your XABF does. You're not that powerful! He is making HIS choices and the only thing you can do is step waaaaaay back, let him do whatever he does, and focus on yourself. It's not up to you or his sister or anybody to "help him". *IF* he ever chooses to find recovery, it'll be entirely his choice.
Now, speaking about YOU, what do you want in life? Where do you see yourself in 5 years? How do you plan on getting there?
Have you considered going to Al-Anon to get the support you need?
I know this breakup comes as a shock, but I'd venture to say that you're being given an opportunity to examine yourself and why you are with someone who is this toxic. Perhaps giving "Codependent No More" a read might be eye-opening...
Keep posting and reading as much as you want. That's what SR is here for.