On the fence about leaving

I have been toying with the idea of a separation/divorce from my ADHD husband for a few months now but I can't seem to come to a solid conclusion. We have been married nearly 4 years, together 6. He is a generous, kind man and a fun person to hang out with.  When we met, he had all kinds of dreams and ambitions for the future, which I mistakenly took as realistic and achievable plans. Unfortunately, he also has what seem to be common ADHD issues as well, so I have slowly found out that his dreams are just that: dreams, never to come to fruition either due to lack of ability or lack of focus. 

In the last year, he has lost 3 jobs due to poor performance. I have had steady employment and good (not great) income since college. I do 90% of the housework, I worry about all of the financials, I make all of the plans (social and otherwise, even after encouraging him to do more of it), and I make 100% of the decisions (not out of a need for control). It's a mother/child relationship. Admittedly, I shouldn't have taken on that role so that is my fault too.  It actually feels like it's my life and he's just along for the ride (and not pitching in).  I'm stressed out all the time and have started going grey and losing my hair (I'm 32). I've talked to him about these issues for our entire marriage, and his reaction would range from blowing me off to temper tantrums. Our life together has been unpredictable and unstable. If it wasn't for my frugal nature and steady paycheck, we would be in serious trouble but fortunately we are not. We just don't have much in our savings account and can't afford the things that need to be replaced.

After this recent job loss, I told him I no longer have the emotional capacity to deal with all of this - it's been non-stop stress for most of our married life but it's been especially intense this last year. I had to get on anti-depressants for the first time in my life. I told him he needs to change or I'm leaving. To his credit, he went to a few counseling sessions and has started to share in the housework. The problem is, though, that I have seen him make temporary changes in the past only to fall back into old habits.  I feel I've lost all respect for him and I don't have faith that he can make permanent changes to the extent that I need him to. I need a partner, not a child. I need stability - financial and otherwise. I need someone I can lean on and who can take the reins every once in a while. We don't have kids, although we've tried. But after learning more about ADHD, I found out that it is heritable and I just don't think I can handle a man-child and an actual child with ADHD.

I'm not afraid of the logistics of leaving: my parents live in town so I can land there for a bit, and my job provides enough for me to be ok. I just don't want to make a decision that affects the rest of our lives based on how I'm feeling at this season of our lives, especially if the changes can be made.  But then again, divorce has crossed my mind throughout our marriage, just not to this extent. Marriage is important to me, but so is my mental health. He really is a good person, and I care about him and don't want to hurt him. I just can't see myself dealing with these issues for the rest of my life. I feel for him because he hates living with ADHD, but that doesn't make it any easier for me.  Does it get better? How long should I wait to find out? I realize nobody can tell me what to do, but anecdotes help.