OP, i mean tbis very kindly as you are young.
Unfortunately you are in a hazy of motherhood, exhaustion and long term horrific domestic abuse.
This is a really bad man.
You can't see it because of youth, exhaustion and confusion.
But you will.
You will come to a place and be so disbelieving of what you tolerated and were put through.
He is just abusive scum whose mask slipped once you became pregnant.
You are not the first nor last woman whose story this is.
He's a really bad man.
Don't be surprised if he becomes viciously nasty when he realises you are serious.
He might threaten you with taking the children.
I would say you have absolutely no idea how evil he is.
I would highly recommend you talk to Women's aid.
Tell your family and friends the truth.
Don't be afraid to call the police if necessary.
If you were my daughter I would want you away from him.
Let him have this other woman, be glad if he wants to go easily.
You are only wasting your life staying.
Your children will soon be an age that fully get they have a totally absent father.
You can do this.
Reach out for support and tell the truth.
He's an angry abusive man.