This issue is pretty much the only place where the fork in the road divides DR and me.
DR would tell you that your partner “has to” be on board for it to work.
My position is: I’m tired of waiting for hell to freeze over, and it’s my life too.
Therefore, in my household, he makes 97% of the money, I control all the finances. We’ve tried it joint, and we’ve tried it where the situation was reversed, both were disastrous. If he sees it, he spends it. (He’s a free spirit, I’m the nerd.)
It sounds like your situation is not quite so black and white.
If it were me, I would set firm boundaries on the money/debt which impacts you both, and your family as a whole. I would set clear goals for the family (i.e., when you not her are going to be out of debt,) and when you both (mostly you) are going to start working on BS3 etc.
Even if she is not interested in doing BS2 for her debt, and face it, you already know you can’t force her, she can still be contributing towards your BS2 (by way of increasing her contribution to household money), and joint BS3 and beyond. At least you will be out of debt, and as long as you’re not legally liable for her debts……..I drew a VERY BIG THICK line when HIS spending meant I could not put food on the table for MY kids (yep, I’m using specific pronouns deliberately), or keep the lights on for MY family. That’s when I stopped being a victim, stopped waiting for hell to freeze over, and took control back over my life.