24hourMOMMY I have had similar said to me and I know the humiliation. There is nothing behind it but cruelty.
No kindness, no love. No maturity either, and no sense that a relationship has to do with anything but his own whims.
In short, the problem here is not your weight, and it wouldn't be your weight even if you tipped the scale at 11 stone or more.
I weighed 7 stone on my wedding day standing 5'5''. I was underweight -- it's about what you would expect the average healthy 12 year old boy to weigh, but I have a small frame and I was extremely fit back then. That sort of weight and fitness level is not sustainable through pregnancy and breastfeeding and all the sleepless nights. exH decided I was fair game in pretty much every aspect of my life, and my weight gain (to a healthy BMI of 23) was no exception to his barrage of criticism.
There are plenty of waifs out there if that's what your H wants. Assuming he himself isn't as young as he used to be, I suspect most of them would laugh at him.
Please sort out how you will be able to manage financially, and start looking forward to the rest of your life, without him. It will get so much better you won't believe it.
You can visit the CAB and have half an hour free with a solicitor.
You are going to need some therapy too, after what he said. That was an assault that cut to the heart.