I speak from the experience of having list a career due to a diagnosis of epilepsy.
I was an on-site architect before my diagnosis.
After a couple of years of depression, I would have done (and really was going to do) what your husband wants to do - upheave the whole family to do more, specific training.
I didn't.
Because I had children with SN's and disabilities that I couldn't uproot from their support networks.
Which is why I think your DH needs a reality check. This just isn't going to work.
If your DH's epilepsy is such that he still can't hold a driving license (you only have to be seizure free for ONE year), and you foresee that he won't have a car or license for the duration of an MA and Phd, then his epilepsy isn't that well controlled.
Epilepsy can and does get worse with stress. Taking on this much studying at the same time as having a family is incredibly stressful, unless he is planning on opting out of the shitwork of having children.
Which isn't acceptable. Leaving you with all the hard work is not on. I truly get where he is coming from emotionally though, it knocks the stuffing out of you to be unable to do the career that you had wanted to do, for YEARS.
It is VERY hard, as someone with epilepsy, to get work in ANY job. All the jobs I have had post diagnosis have been entry-level retail jobs.
I am kind of on the fence here slightly, I can TOTALLY understand your DH's point of view, his employment prospects with epilepsy that isn't controlled enough to hold a driving license are frankly shite. REALLY shite.
But I am falling more on your 'side' so to speak, because you MEED your support network around you when you have had MH issues, AND you have a DC with disabilities. Moving would be the worst thing ever for you.
I think he needs to understand that if his epilepsy worsens, which it can and does, then an MA and/or a Phd might not be possible to complete for health reasons.
Currently my epilepsy is at the point where I cannot work at all. At other times, I've managed to work PT, but FT work always puts too much strain on me and worsens my seizures.
This is, basically, a REALLY crappy situation for your family to be in, and I don't know how to resolve this in a way that meets all of your needs, because their isn't one.
Either way, one of you is going to have to sacrifice a LOT. Either you or your DH. But I can't tell you who would feel the most resentful in the long run.
Whoever does the sacrificing, be it your DH sacrificing his dreams of an MA and a Phd so that you don't have to move, or you sacrificing your support networks and counsellor (I know how hard it is to find the 'right' counsellor), one of you is giving up everything.