Slightly different situation, my husband relocated abroad on his own about a year ago (on a permanent contract but insecurity as to the future location of his work, so we decided that all of us moving with him would not be a good idea). I was left alone doing a full time PhD and two children to look after, and paying rent for a large house in a different town to my university (I'd commuted ever since starting my PhD, nobody had ever asked me about this, and I have several PhD colleagues who do the same), which was a strain, organisationally and financially. In fact, in the end, I decided to move to a third country, to the city where my parents and inlaws live, and it appears to have been a wise decision in these circumstances (despite the temporary disruption through the move, which shouldn't be underestimated...). Kids are settled in their schools and happy to be near their grandparents, I have extra support from them, husband has slightly shorter weekly commute, living expenses are lower. I regularly communicate with my supervisors via email and skype and can travel to the university every couple of months (thanks to cheap airline connections), at about the same cost as commuting on a twice weekly basis from my old home. However, I had already finished my main fieldwork before moving and my funding had almost ended, so I have 'writing up status' now. I would also recommend waiting until the 'maybe' is definite (and perhaps asking your husband to try and postpone it or avoid it altogether?) and then try to find a solution that allows you to complete your PhD (maybe possible to take a sabbatical, if the relocation is temporary?), I certainly wouldn't let this put you off starting!
