I can understand what you are going through to a point. I am a disabled Vietnam veteran, and I too have major back problems. The first sensation I am aware of in the mornings is pain, and the last sensation I remember as I finally drift off to sleep is pain, so see I do know what you are going through as far as the medical issues with your back. I am on heavy medication on a daily basis, and this only brings the level of pain to a point where life is bearable. I am sure your scars are worse in your eyes than in others, as we are all self conscience of our own maladies, and scars. Without clothes, due to other medical issues I have dealt with in the past, I feel l look like some sort of Frankenstein, but I go on.
Two years ago when I was at the pain clinic in Nashville's Vanderbilt Hospital, the doctor in charge told me, after looking at my MRI's, she didn't know why I was not in a wheel chair due to the problems I have. I told her, I could give up, quit, and wallow in pity, but I would still have the same problems, and that would bring just that much more problems to what I already deal with. I too have good and bad days, and I am more accurate with when rain comes in than the weather people, but I deal with it, as I have no choice, other than what I said above.
I think one of your major problems right now is depression, and I think you need to talk to your doctors about it and see if there is not something they can give you to help you with it. Depression is something many deal with, and others seem to be ashamed to admit to. It is no different than diabetes, as your body is needing a chemical that your brain is not producing enough of like the insulin that the body is not producing in a diabetic. Medications are there to help fill that gap, and it takes time for it to get in your system, but it could help you deal with your maladies if you would give it a chance. Again talk to your doctor about it, and if he/she feels it is something you may need, go for it.
As far as your husband goes, he may very well be having an affair. In this area, maybe you need to go see a lawyer and see where you stand from a legal point of view. If he has been the sole bread winner since you have been married, there are ways, (alimony/spousal support) to help you in this area. I don't know what your situation is, but there is Social Security disability as well as SSI, which may wind up being an option for you as well.
If the two of you can't work things out, then you have options and only you know what direction you want to take, but people only treat us the way we allow them to, and you don't deserve to be treated with disrespect, and you should not allow him to get away with this treatment!
First and foremost you need to do some straight talking to your husband, ask direct questions that he can't answer just yes and no to and find out what is going on in HIS mind, and then it will help you decide what you need to do at this point in time.
I hope this helps, good luck, and do keep us posted. These boards are a great place for support, even just to vent if that is what you need to do.