I would see a solicitor asap - it's only sensible, and IMO your Dh is being quite unreasonable to be 'horrified'.
I have heard of more than one case where one partner trusted the other to do the right thing, only for the surviving partner to remarry quite soon and leave everything to the new spouse, and nothing to the former spouse's children.
In one case there was fairly early dementia thrown in, and although there was already a fair will in place, the new spouse was able to manipulate the other into making a new will, leaving everything to her.
The disinherited children could do nothing about it.
Please do it asap.