You do not have to pay tax on the money. Payments, transfers, or sales between spouses are never taxable.
Before you make any more major financial moves you should talk over everything with your lawyer. It's not clear from your post whether the buyout has been completed. If not, talk to your lawyer before you go any further.
I am not a lawyer, but it seems to me that you should get your money out of that joint account and into your own account ASAP. If it hasn't actually been deposited yet, maybe it should never go into the joint account in the first place. Talk to your lawyer.
