Is there another, less costly alternative you maybe haven't thought of, yet?

Can you ask him why, specifically the cost of the class is an issue? Maybe he is worried about his job, or recently took a hit on his 401K. I know that my family has been a LOT tighter with money these days.

What is your back up plan if you find you cannot take the class? You seem pretty determined to take the class - and I know what that is like because I get something in my head and when it is already decided I get very cranky about thinking of alternatives. But at the same time, if your husband's concerns about finances are valid, then wouldn't it be a wise decision to "freeze" special expenses like classes and luxuries, at least for a little bit? Can you put it off? Can you do in-home training on your trainer with similar effect? Can you invite some like-minded friends over for a couple of nights a week for training in your house?

Just trying to think of some creative alternatives... I know it is hard to suffer from depression and I also know how ultra-focused one can be when one thinks there is only one way out of it. But often in the intense focus of "the cure", we miss the subtle things that might help us even more. For example, have you considered that your husband's reaction might in fact be a reaction about your whole last few months? Could he be feeling left out of the process? Could he be feeling hurt because you want to spend money on a class instead of relying on him to help you get out of your blues? I know that my husband would very much like the world to consist of only immediate family - he wishes we could live in a cave. External influencers, including positive ones (like this board) make him suspicious. Like, a bit of a threat. Could your husband be seeing this "one and only" solution as a threat?