sunshineandlemons - what would you like for your future?
Do you love where you live and want to say in your current situation (if it were not considering your children's education)?
Do you want to return to the uk for yourself?
Do you want to go back to work?
It sound's a little like a mid-life crisis, and perhaps seeing it as such would help you to work through what you want?
Practical considerations regarding your children's education are clearly going to be a part of your concerns, but it might be important to look beyond, to when your children have left home (with a 6 year old this might seem a little premature, but it really is not!).
When you have decided which country you and your husband wish to live long term, it is after this that you need to look at your children's education plans. If you wish to remain in your current country long term, then it changes things with considering your children's education.
If you wish to eventually be living in the UK in older age, then you need to think about moving sooner rather than later, as your 11 year old will need to be moving over in the next two years. But if you have another 5 years of mortgage on your property in the UK, then you and/or your husband will need to be certain of getting work locally to your uk house. How would you feel if neither of you were able to get work, what is your back-up plan for your children's education?
Basically you need to make your decisions on your longer term plans with your husband. (does he wish to return to the UK?)
You are not a failure for doing what is right for your family, having a career these days is not important, as people do not generally stay in the same job for life unlike years ago. Transferable skills, you do have language skills, cultural experience, self-employed, as well as being a good mother.