He changed when I got pregnant

When I first met my husband, deep inside I knew he would be the father of my children and my life time partner. 

He was the man I always dreamt of, he introduced me to his family and friends. This made me think he was serious with our relationship. To appreciate his love, I decided to give him a child. 
   
Unfortunately, when I conceived, he completely changed. He started coming home late and so drunk, sometimes he wouldn't come back.

One day he locked me in the house for 2 days with nothing to eat, when I tried calling him, he did not pick until I connected to my sister who ran to my rescue. 

I've tried to make the relationship work but he isn't changing.

What should I do?

Madrine