I get your point, but I also think your attitude to your DiL leaves you at risk of cruising for a bruising. Pregnancy is not an illness per se, but you can still be very ill when you are pregnant.
Some pregnant women experience such severe nausea and vomiting. They are unable to keep food or drink down, This excessive nausea and vomiting is known as hyperemesis gravidarum (HG), and often needs hospital treatment.
The Duchess of Cambridge suffered from it in her first pregnancy.
There are other conditions pregnant women suffer from that makes them ill and can require hospital treatment, pre-eclampsia, for example that can lead to loss of the child.
I agree your DiL was a tactless and shouldn't have said what she said, but if she is as ill as she sounds with 'morning' sickness, it is easy to say something that with hindsight she may realise was not wise.
In the meanswhile if you and your DH react to her in such an antagonistic way, I forecast that 9 months from now you will be posting on the estrangement thread, asking why your DiL will not let you see your grandchild.
Ask yourself, when feeling ill or under stress of any kind have you never ever said sonething you later regret?