Life situations are so very hard to manage, especially when there is so much stress and tension involved. Change is never easy, but it is the only thing that is constant.
I believe that what is best for our children, whom we have been blessed with, along with the absolute responsibility of their well-being, should always be the deciding factor. But, sometimes we mix that up with our justifications to make what we want look noble. You really need to get this straight. Your present living situation has been a constant for a long time and all of you have survived.
I do think a trial period is a good thing. How often do we have a chance to just try things out? It could put many things into perspective and give you and your DH time to make really good decisions. The job sounds like a wonderful opportunity, that if isn't tried may well be a regret that could fester the rest of your life.
I will have you and your family in my prayers. HE seems to always have the answer for me, I pray HE will help you with yours.