Grace,
I agree with what a lot of the other women have said to you about getting out and this guy is NOT going to change. If you want 'answers' as to why you can check out this book called "Why Does He DO That? Inside the Minds of Angry and Controlling Men". The author is Lundy Bancroft.
He addresses a lot of the questions you are raising as to 'why' and 'will he ever do this again' and 'he was so wonderful in the beginning'. He does a fantastic job describing all of this in wonderful detail.
He is very to the point and probably will not say what you want to hear which is, 'Give it time. It'll get better and Love will conquer all." He talks about the woman's safety and how the best thing YOU can do for yourself (and him) is to leave.
You said you don't have a job, or a home or whatever you said...YOU HAVE TO LEAVE...NOW! Go to a shelter, talk to a friend. You have to really dig deep to that person you say is still in you AND she IS! The problem is that that person has been stifled and you've lost confidence. Get angry! and chanel that anger to help yourself get safe! You're so worth it!!!