My sympathy to you for the problems you are going through. However absurd it may seem to you, for me you are on the right path. You have a depression problem but you are addressing it the right way. First curing the illness, and then you have clear in mind that depression is triggered by your real problems. Having said this, I suggest that, if possible, you see the situation in steps:

First you have a marriage that must be reconsidered. it depends mainly on your husband, can he work his problems and find a new meaning in your marriage (he seems to have lost it now).
If you fix your marriage, all the otehr problems will be eliminated, so you really have to focus on that.

Uh, and by the way, I can't see any trace of FAULT on your part, really. YOu are just trying to make up your mind about what can make you happy, like everyone.

The best of luck and let us know