"If I sell the house, it means my boys have to move to a new school and I JUST got them settled in to their new school here (they had to move to a new school when we moved here)."
You could always rent a house, in my hood a house goes for 800k but you can rent one for 1600-2000. Or what about rearranging your house to rent the basement to a tenant (or an exhusband

about the dream house, dreams change.
"DH has been "diagnosed" with depression by his doctor, he has medication for it, he goes to a weekly support group and to counseling, so he is trying to get help, (maybe I'm being unfair?). "
what about looking into some residential treatment for him...a month away to get really back to normal, the traditional OHIP paid vacation.Also has he had a physical, depression can be a symptom of a physical issue like heart disease etc.
Sounds like he's using depression to gain control, you are right sounds not much like depression.
"No hot lunch program at the school - maybe I can suggest it to them!!"
Mine isn't run by school its a private company, there has to be service in your area, ask the principal.
What about having dh move in with his mom and only come over when he has the energy to be positive?
Also you are burning out, please put on your own oxygen mask or you will not be of use to anyone to help them put on theirs

"I do find that the hardest time is when I'm at work. My boss is so totally unreasonable and it is so extremely stressful"
Easy get your boss recruited out, look for their cv, profile on linked in, shop it to headhunters

Then take over her job, boss issue solved

"Unfortunately I'd read the job posting wrong and it was not the job I thought (not a job I'm qualified for) " APPLY ANYHOW.
the worst thing that happens is they don't call you back and most of us are more qualified than our resume suggests!