Yes, this is abuse. It's a pattern, it has gone on over some time, and the aim is to make you feel terrible about yourself.
Telling you he will take DD away from you is horrific and chilling.
You mention the extra weight you are carrying around. It's not four stone. It's him.
You are conscious of the weight because he is hacking away at your self esteem. Maybe somewhere deep down you think if you could lose it things would be different. Maybe you believe there is something about you that makes his contempt for you inevitable.
None of what he is doing is about you.
You can't control it.
You didn't cause it.
You can't cure it.
An abuser's life and thoughts and speech are all about him. His anger. His deep self hatred. His own twisted nature.
Call Women's Aid for help and advice about leaving the relationship. You need to take both yourself and your toddler away from this angry, loathsome 'man'.
0808 2000 247 is WA number.
Call and leave a message, or you can go to their website and find the email address where you can send an email with details of the abuse you are suffering. They will call back - give a day and time when it's safe to have a conversation.