Just know that my primary goal is to stick together.
Is she in effective and progressing therapy? If not, then you will likely have to adjust your goals.
I'm not saying setting better boundaries and improving your communication skills won't help, it can. For a while, but long term it may not be enough. A marriage can be healthy and functional only if both are working to make it work. Once can't do it alone. You can't drag her kicking and screaming away from the dysfunction.
In other words, the past is a good predictor of the future. If things have been progressively getting worse and worse, that will continue. In general it's almost as though a pwBPD has to push boundaries and keep pushing, reciprocation isn't a consistent part of the playbook. Any consideration and relaxation of boundaries only enables more incursions.
I guess you can see that it was unwise to keep so much money in a joint account. Going forward, can you keep any excess money in a personal account she can't raid at a whim? There's nothing illegal about that if you are married, remember, she already did it to you. If she complains, well, that can be one of your new boundaries, you have to protect the remaining marital money. And if she really complains, then tell her she'd have to return the $$$. Alas, her emotional perceptions will carry more weight with her than your logic and reasoning.