Non-ADHD partners with anxiety or depression, please advise. Thank you!

I feel like I'm getting closer to a crossroads.  I've been toiling for years (yes, YEARS) to improve my ADHD symptoms.  I feel fortunate to have good health insurance that not only pays for medication, but also alternative treatment via a Naturopath, as well as for therapy.  Therapy and meditation have really brought me to the next level.  And scarily, it is at this level that I have realized that this marriage is not all about what I have to do to improve, and now I am learning to set boundaries and express my wishes to a spouse who has had his foot out the door for years. 

My therapist is amazing.  I've suffered through several duds who didn't get me, didn't push me, and definitely didn't have an adequate understanding of ADHD.   When I described his behavior and asked for feedback, she has a strong sense he is experiencing anxiety, depression, or both.  I've expressed to him that I think he needs counseling, that his anxiety and moods are an issue.  I feel he has depression because he resents me for past mistakes and refuses to forgive me for not putting more effort in our marriage early on (I was young, dumb, and clueless with untreated ADHD).  I feel he has anxiety because he stresses a lot.  He has somatic issues that corollate to either.  

He used to threaten me frequently with divorce, but through counseling, I called him out on it, and he hasn't done it in months.  He did it on a regular basis for half our marriage prior to me calling him out, roughly 10 years.  He's pretty critical, but I've noticed his criticisms are getting more and more trivial, and so does my therapist.  Thinking distortions?  He has them all.   I honestly think his insecurities started with a father who moved overseas for years while he was a child.  Abandonment issues, for sure, and I think he deals with them by keeping me at a safe distance.  I am ALWAYS working on something.  I ALWAYS have personal goals to achieve and plans to achieve it.  I want to become a better person and I honestly am.  He cannot see it because he is protecting himself and views me through the muddy lens of whatever is going on in his head.  

My therapist and I shake our heads because there is no substance abuse, no domestic violence, no financial ruin, we have both had steady jobs for two decades, and no infidelity.  The only thing standing in the way of our marriage is his anger, resentment, self-righteousness, and frankly, mental health issues.  I do not know what to do.  He might say that if he has anxiety and/or depression, that I am the cause.  I feel that the fact he won't get help is the issue. 

I've finally realized it doesn't matter what I do.  Even though the house has been cleaner than it has ever been for a month, and I'm not even struggling, thanks fo a great book, he managed to take that and turn it into me being able to do the things I deem important, and only once I deem it important, does it get my attention.  As I said to my therapist, that's true for everyone.  You cannot outwardly impose true, meaningful change on another person.  They have to want it.  But equally relevant, they have to know what they don't currently know in order to change the situation, and I didn't flippin' know.  I can clean the kitchen, but the rhythm of cleaning a house daily has never made sense to me until recently.  It no longer feels like a farce, but I know it's officially a habit.  BUT now that I actually understand, I get how simply it appears to you NON-ADHD partners out there.  But instead of being impressed with each new change I make, he finds a way to diminish it.  And my therapist said (and I totally agree) that he can't have me improve while he's stuck because that means he needs to change, which means he has treated me pretty poorly for a long, long, LONG time.  And it's more important to be right than happy, clearly.  *Sigh.*   

Any suggestions on how to get him help without alienating him further?  He really is a good person, but lost in his head.  He didn't used to be like this.  But I cannot live like this forever.  I don't want to be a poor example to my children to stay in an unhappy marriage for an eternity.   But I don't want to quit on us, either.  Y I know people go through rough patches and I am willing and able to do some heavy lifting, and I have been. You can see my dilemma...