Btw, I wonder if it might help to think of and talk about your potential for illness differently, translating it into a roughly equivalent physical illness?
I think mental illness can be hard to acknowledge, manage so as to avoid, or quantify risks about, partly because you're wishing it away, partly that it's poorly understood by most people and not easy to talk about but also because while you're well it doesn't seem to be there at all.
If you had say a history of heart disease, with narrowed arteries and a set of risk factors, you'd know the arteries were really and actually furred up, whether you were chosing to think about them or not. They'd be a fact.
Then you'd have a set of risk factors, things to do and things to avoid (diet, exercise, stress etc). You'd know the consequences of doing the wrong things could be catastrophic in a way that might or might not be recoverable from and recovery could be very gradual and come with impairments and increased risk of relapse.
You, your DH, anyone, would be actively supportive of your maintaining your healthy regime, would alter normal domestic patterns to accommodate this and would become concerned quite quickly if something seemed to be slipping in the wrong direction.
It would seem a very unusal spouse who would say 'no, you just carry on eating burgers, finding no time for exercise and getting stressed out at work and, because of disruption to your study, prolonging your time in that job. Sure, there's a serious risk of a heart attack, leaving you incapacitated for a year, or worse but you know, I love my job and I just don't want to talk about changing things to make our lives work better for your health, so as to secure our children's care and happiness, in fact you can forget your self-indulgent 'lifestyle' ideas, I will not hear of changing our current set up in any way taht affects my career-lifestyle choice.'
Well, haven't I just described your situation, more or less exactly, from what you've told us?
I think you need to make your health vulnerabilities real to your DH. Maybe try a 'physical translation' like that, or get him to talk to a professional who can talk through what depression is and what its implications can be. I don't think he'll ever fully grasp it coming only from you because he hasn't seen you ill and won't want to believe it.
He really, really needs to understand that it's the opposite of something that can be left until crisis point is reached. Doing that is actively choosing to make it much, much worse.