It sounds to me like you really need to sit down and have a good, honest chat about why you booked this holiday, before you go away OP. You've probably both said things in frustration and tiredness that has undermined the reasoning behind why you originally chose to go, which is why you're left wishing you'd never booked it, but it's done now, and you BOTH need to accept that you made a mistake in rushing into going away this year, rather than taking your time, saving up, and taking the holiday next year. You also need to make up your minds, that after all the hard work you've put in, and the resulting stress, to have a lovely time while you're away, and that if the slightest thing goes wrong, you don't start blaming each other. Make sure that you do lots of homework between now and when you go away, so that you know all of the things that you can do in the area.
As a previous poster said, you would have to eat and pay normal bills for living if you were at home, so don't worry about every penny you spend while you're away, it's just money you would have spent anyway, with perhaps a few little treats thrown in. It sounds like you only have one small child at present, so hopefully there won't be demands from older children to do things which will cost additional money. So just make up your minds to enjoy it, hopefully the weather will be lovely, and if that's the case, you can have a great time just relaxing, with maybe some long romantic walks, and perhaps a picnic thrown in. You don't necessarily have to spend a lot of money going to bars while you're away either, go to the local supermarket, and buy fresh bread, and things like local cheeses, fruit, and wine to enjoy, these things always taste nicer away from home.
It does sound though as if your partner wasn't as into the idea of going abroad as you were OP, perhaps he got excited at the time, but has then had time to reflect, and with the extra work, has begun to regret being impulsive, but if that's the case, you need to point out, that it was a JOINT decision, as presumably you wouldn't have booked it otherwise. I hope that it all works out, and you have a great time, and then in the future, if you find you BOTH enjoy it, perhaps make plans for a nice holiday every other year, and then save towards it from the moment you get back.