This disorder is a HUGE test of anyones ability to cope. I don't blame you for feeling like you do. It's completley understandable. As far as a diagnosis goes, I would focus on what the doctors tell you. Reading this board and all the possible reasons for vestibular problems can make you crazy. You shouldn't try to diagnosis yourself. There is nothing wrong with educating yourself but if you try to diagnosis yourself you will go crazy. I think the simple fact is a lot of symptoms can be the same for many disorders. You may have headaches just from stressing over all of this. Try to figure out what is wrong with your doctors not with this board. I'd use the board for a way to get support not try and figure out a diagnosis because that is impossible and will make you nuts.
Your husband is only human and he probably feels really helpless because he can't make you feel better. Maybe tell him you don't expect him to fix the problem, you just need him to listen. I would also try ( and I know how hard it is) to spend maybe 30 minutes a day doing something that will get your mind off of this. You have to find a way to find something that will make you happy or at least distract you. Maybe think about all the things in your life that you feel grateful for (like your husband, children if you have any, ect...)
I would continue with the therapist, because you have someone objective and detached from your life to listen to you. I'm so sorry you have to deal with this. I do understand the fustration and hopelessness you can feel. It makes sense. But you need to try and maybe make small goals for the day. Try to do something you didn't do yesterday. Maybe it's just walking for a minute more than you did before, or anything like that so you can feel like you have accomplished something that hasn't happened in the past. Find small goals, and as you accomplish them that might make you feel better.
Remember you are NOT DYING, and this is not a permanent condition. MOST people DO RECOVER. Unfortunatley it works at a snails pace. That is why taking it one day at a time is super important.
Big Hugs,
Joy