2 thing stand out for me. One was years ago. I'd lost 20kgs and told my Mum. Her reply? "Don't get excited, you've got 20 to go". Way to be supportive.
The other was more recent. After we lost our baby at 12 weeks (blighted ovum), SMIL told me I "shouldn't be upset as we really hadn't lost a real baby". Felt pretty bl00dy real to me. that was 3 years ago but I'm not sure I will ever forgive or forget.