I don't know when you posted but I just came across your post and can totally relate to your overwhelming life. Like you, I suffered with disabaling panic attacks. Like you, in a round about way, I have a husband who is disabled and retired on disability. He has many medical and depression issues. Additionally a Mother who is in end stage COPD and thinks she ready to start taking the morphine, a father who is having a total hip replacement next week, 22 year old son who just moved back home after being away at college for 4 years, and, he is quite addicted to alcohol (actually lost his license for 18 months for driving under the influence. Additionally, I work, but the husband, mother and father are all retired.
Suffice it to say, not only do I understand, I can totally relate. It has taken me a long time but I am in the beginning stages of trying to unscramble some of this mess. Learning to say no, while not feeling guilty about it, is a big one. First thing, you need to get treatment for the panic attacks. There is medication out there to block the attacks and help you feel more in control. Anyone who is capable of caring for themselves, need to. If life is that stressful, maybe your husband might need to put his graduate studies on hold. He's going to be in a bigger pile of shit if you do have a nervous breakdown. You might suggest to him that he be a little more "proactive" in helping to unscramble the mess.
You should check in your community to see if there is any assistance you can get. Maybe you would qualify for fuel, child care, Medicare/Medicaid (depending on your children's "needs").
Figure out what you do have control over; what can you take off your plate, what can you give to someone else; what other resources are out there for you.
And, did I mention I too am in the first several months of preparing for a lapband, which is going by the wayside with all these other things going on.
Remember, if you don't take care of yourself, you will be of NO help to anyone else.
Take care and keep talking with everybody.
Marcia