This letter should be sent to her cheating husband. I think she forgot who said their wedding vowels and then broke them. The betrayal from a husband is much worse, especially during a time she was unwell and needed him to be a real man not a sullen boy who missed being the centre of female attention. Yet she thinks it was the other women who “got in the way”. Good luck with that.
As someone who can not function on minimal sleep this is silly idea to force you both to suffer.. I agree the workload should be shared. So pump, store a feed in the fridge and then your partner can take the next shift while you get some proper decent sleep longer then 4 hours. And yes that can continue even after one of you goes back to work. It’s not forever. Taking shifts is dividing and conquering and fair. What’s not fair (or smart) is torturing both parents at the same time.