I do understand your upset at having what you thought was going to be your future all tipped on its head with the prospect of this new job.
But, like many others have said, though not ideal, these are the sorts of working conditions many of us and/or our partners also have to put up with - or worse. I think long, inconvenient hours are inevitable when house prices just keep going up and up ..... so people end up commuting for hours (because they can't afford to live closer to work) and/or they remain in a job with sh*tty conditions because they can't afford to drop to a lesser paid job with better conditions IYKWIM.
Yes - it sucks. The days of leaving at 8.15 and back in time for tea at 5.30 are long gone for all but the very fortunate few.
My DP leaves at 6.30 - and has done for years. If we're lucky, he gets back at 7.30 but his is the type of job where he's expected to stay as long as it takes ..... so it's an hour or two later reasonably often. He's also perpetually "on call", should he be required. In practice, this hasn't impacted too badly, but the interruption and intrusion in our short time makes me really resentful. On top of that he travels abroad quite frequently, for up to a week, so guess who is then left with 24/7 responsibility (and also feeling like I've got the sh*tty end of the stick when he gets to eat out in nice restaurants and bars and maybe squeeze in a little sightseeing too) ?
Unfortunately, for all these expectations, my DP doesn't work in the city and is no way paid a "city" type salary or anything remotely close. If he was it might be some compensation and we might have been able to have more than 1 weeks holiday in the last 5 years. Nor do I have the option to even think about getting any sort of help, be it an au pair, nanny or a cleaner.
Anyway ..... I know that doesn't especially help you, but it is a reminder that 100s of 1000s of people live like this permanently, without any option of working closer to hokme for one or two days a week, which would obviously help, and cut down on commuting time.
I hope I'm not offending you - I don't mean to, because I'm sure you know all this and I also appreciate that if long distance working has caused problems in your relationship before, you're understandably worried that they might again. However, I wonder if your resentment and concern is in any way connected to your DH's reaction to this prospect ? What has he said about it ? ...... do you feel that perhaps he isn't being as assertive as he could be at work regarding previosuly "agreed" conditions, or do you feel that perhaps he's just taken this news "lying down" irrespective of the difficulties it might cause ? .....
..... when I stop to think about it, I feel quite resentful about DP's hours and the expectations placed upon him, but I also know that he could NOT get a job paying what he earns now (and we need every penny) closer to home, and I also understand that in his particular skills sector, his conditions are nothing unusual. I don't feel that HE, personally, is responsible for the situation we find ourselves in.
In other words, I don't feel his employers are taking advantage of him - it's just that long hours go with the territory. If however, they were to introduce something "new" (and disvantageous and/or unreasonable for no extra money) and I felt he'd not at least tried to reach a compromise, I'd feel very angry/hurt if the "price" of meekly accepting such a proposal without murmur was our family life. Though even then, at the end of the day, if someone simply can't get another job, most people would have to put up with it unless the change(s) itself was illegal in some way.
I can only echo what others have suggested and advise you to implore DH to negotiate the best possible arrangements (for you all) for him to complete this job.