Please Help! I Did Something Bad To My Lovely Wife

Husband said he's hurt his wife and he doesn't want her to use the opportunity to turn against him...
My wife I and have been married for five years now. All this while I never hit her, no matter what happens, but I don’t know what came over me, I hit a few weeks ago and can’t forgive myself.

We were involved in a heated argument and though I had never seen her react the way she did, all of a sudden I lost my temper and slapped her in the face and used some terrific words against her; since then she has asked for some space.

I would never hurt her, she is the best thing that ever happened to me and I love her and can’t live without her.

She said she has forgiven me but I can tell by her looks that she has lost some love for me... 

This hurts me the most. How can I make this up to her? I told her that this would never happen again, that I was sorry and loved her with all my heart. She said she loves me and was not going to leave me but she needed some space.

Please I really need advice from anyone who has had a similar experience or anyone out there, who has an idea for me on how to make it up to her, or will our marriage be like this forever? 

I cannot bear this any longer.