Felicia, sorry you are feeling so terrible. Try to stay calm and know it will pass. Try not to torture yourself by wondering what he is thinking or doing.
Didn't this man say to you, "I choose alcohol over you"? That's reality. It sucks but it's reality and you will probably never get a reason other than he is an alcoholic.
You are a good and caring person. You deserve someone who appreciates you. Believe this and you'll get past the heartbreak. Keep posting and please take care of yourself!