Hello, ThisNameWasNotTaken, welcome to My Support Forums.

Talking to your therapist and to an attorney sounds like a good place to start. If I were in your situation I'd also want to do a lot of documenting ahead of time. Even if you couldn't keep your physical possessions from being damaged/destroyed, storing pictures of everything in a safe place could at least make it easier to hold her to account.

Could you set up a separate document cloud account just for you, and copy everything from the shared account into it? Your lawyer would be able to tell you if there are ways to prevent one owner of a joint bank account from locking another owner out of it (or draining the account without the other owner's consent). State laws probably vary on who has the right to lock whom out of the house, and what recourse you'd have if they did.

I see something of a tradeoff here: the more thoroughly you've prepared ahead of "the conversation," the more disrespected your spouse is likely to feel, and the more justified in resisting you at every turn and taking out her wrath on anything that's still within reach. On the other hand, the more you include her in your decision ("Do you think you might feel better not staying married to me?") the less vengeful she might feel -- but also, the more opportunity she'll have to head off your logistical preparations with her own.

You know better than anyone else how much risk you'd be willing to tolerate in the interest of a more amicable parting -- or how willing you'd be to look like the "bad guy" in the interest of more thoroughly protecting yourself.