I personally suggest trying to communicate with him one last time about it before breaking up. Tell him how you feel clearly, remind him how patient and supportive you’ve been for him, clarify you’re not going to give him anymore money until he makes some serious financial stability changes, tell him he should at least pay you back in full, and clarify the fatal toll his addiction is taking on your relationship with him.
If that doesn’t work, leave him for your own sake, knowing you tried what you could out of the goodness in your heart.