Why is he so bad when everything else is?

Is it normal for the person with ADHD to be horrible in a crisis?   Not only is my husband terrible in a bad situation, but he often makes it worse.   I was just talking with someone the other day about how I was dying in the hospital after having my first child and he thought it was appropriate to joke with the nurse that I was just faking it. Yes, the nurse took him seriously and yes, I could have had a stroke.   Or the time we had issues with a contractor and he decided I was being irrational and he and the contractor forced me (by badgering constantly for three days) to sign a document saying that I was satisfied with the work (we needed that to release funds from the bank), and then a few weeks later our brand-new porch fell apart in the rain and we had to sue and got a lot less money because. . . wait for it. . . the contractor had a document saying that I was satisfied with the work.  

It's like this with every bad situation.   I don't know if it's because I'm the rock and every time he sees me as vulnerable he wants to have the upper hand, or if he just panics and does the wrong thing.  Then it sets us off in a cycle.   He does the bad thing, I'm furious, but also in a place where I can't leave him at that moment because of financial or stress issues, I dig myself out of the situation and by that time, he's fine.  He's apologized and things are back to normal except that a few months earlier he did some thing that I would have left him for on the spot if we were just dating and not married.   And the things add up.  

Right now we have been in dire financial straits for years, basically because I have been trying to get him to actually do something about it, instead of killing myself to keep up with his irresponsibility.  That didn't work, and I just had to get a new job.  I slowly started taking the steps to get myself in a place where we can divorce.  And he didn't even understand that I had to get the job because of him.   He's like "oh, you wanted more stuff to do so you could keep a better schedule."  No, I got a job that would lead to a new career in about three years (it's grant-funded, so it has an expiration date). 

Guess what happened. After years of begging him to get a new job that would pay him better (and let's face it, he has ADHD - he's probably gotten bored and complacent at that job and it's not going to get better.  He should be switching jobs more often, but instead he overstays his welcome and gets laid off.)   For the first time in our 27 years together, he updated his resume when he still had a job.   We will see if he actually applies to something.   I should be happy, but I'm kind of annoyed that I decided he would never change and I had to go and he changed.  And that's why we've been together for so long.  I decide that I've had enough and he switches gears.  But he never does it before it's too late.   We are now not putting groceries on credit cards and NOW he decides to get a new job? 

Why can't he do the right thing when things are bad?  Why?