Illigal Site Called Novel update there is not official trans they said
you can go to novel updates and search 'the wife is first'. but it's still not completed though
Chrysanthemum garden 》the wife is first
https://chrysanthemumgarden.com/novel-tl/twf/
I would suggest you to read from the start, as I really loved how actually last moments of them has described in novel. It isn't that detailed in manga tho.
Where should I start reading the novel?