Destiny and Marathon saves now applied to wrong account

Hello, I have played Destiny/Destiny 2 since launch and Marathon since launch. I had inadvertently cross saved my Bungie account to my fiancées account, and found out later that it was a permanent connection. Now my fiancée is separating from me and I do not know what recourse I have. I don’t even know the login information for my fiancées account, and even if I did I would not use it after we separated. Is there any way you recover the thousands of hours or progress I have? Any help would be greatly appreciated. Thank you.