Hi Emmabean,
Sorry to hear you are in this heartrending quandry. It's a very difficult situation all round. I can't give you a solution ... you're gonna hafta work it out ... but here's a few braindrops (whatcha get when ya brainstorm) that you could consider if you haven't already done so.
First & foremost, my heart aches that you don't have a support system. Your family & DH need to be there for you, not forcing you into more stress. That is #1 counterproductive. Do they understand the diagnosis, or do they think you are just a lazy whiner? Sounds like the latter. There are different ways to educate folks: send them to a website, have your doc talk to them, find a good book for them to read, or a DVD to watch. Personally I would preview any info I give them, there are many viewpoints on fibro.
Second, I would re-evalutate where you're at medically. Please, please, please have a thorough eval (not just a screening) of various hormonal functions. Thyroid disorders, adrenal malfunction, estrogen issues -- even testosterone (ya, & even for females) --can all play a role, and these are highly treatable things.
Sounds like, even with whatever meds you're on, life is not great. What does the treating doc say about this? If you are not making progress, consider getting a second opinion. Many of us with fibro have been helped more with alternative med approaches than with standard antidepressant & painkiller regimens. If you're unfamiliar with the wide range of treatment options for fibro, I recommend the book,
From Fatigued to Fantastic, by Jacob Teitelbaum, MD, a fibro specialist who is himself a fibro sufferer.
Third, I would evaluate what can be done on the occupational front. While classroom teaching is stressful, have you considered that an ed degree is quite flexible. I know former teachers who consult to homeschoolers, others who took a few extra courses to get certified as educational testers, & that is fairly lucrative, can be done from home. Educators are in demand with companies that produce textbooks, as contributors, editors, and proofreaders. Ed software & companies that do internet-based education need educators, and these are often work-from-home jobs. You may still need some child care, but hours would be flexible ... break things up, work part-time, whatever. And probably the work would have less stress than a classroom.
Don't underestimate the potential value of services to the homeschool community, tutoring, working one on one with special needs kids. A portion of this work could be done bartering housecleaning & child care. Many homeschooling parents are on the lookout for such "deals," and it would be a good one for you. In our community, an hr. of educator time is worth about 4 hrs. of household cleaning, or 6 to 7 hrs. of child care.
Fourth, household responsibilities. Work with your DH to figure out what he does best & consistently & will agree to take care of regularly. Maybe it's mowing, or vacuuming, or laundry or grocery shopping. If you need some counselling together to get this figured out, it will be worth it. Most communities have some form of sliding-fee counselling available. If you are a member of a religious congregation, your pastor/religious leader may be a skilled counselor, and the service may be free. On the other hand, most of us find that hubbies are like puppies: they can be trained to do "tricks" around the household, and generally respond very well to appreciation and petting

for a job well-done.
Find a local fibro support group & see if it holds any potential for support, information, finding a doc, or finding reasonably-priced massages if that's what helps. Is there a massage school in your city? If so, you may be able to get services there at a reduced rate.
Sometimes a little progress on every front can have a synergistic effect, where the result is greater than the sum of the parts. I hope you will find something that works.
Best wishes.