I'm so sorry this has happened to you.
We had to cancel our wedding around three months before the date because my DH freaked out in a similar way. I had absolutely no idea whatsoever that it was coming. We hadn't argued at all, there were no clouds in the sky, no indications of anything wrong. It was absolutely horrendous and incredibly traumatic, made worse by the fact that it was such a shock. So I know how you feel.
Every case is different, so I can only really tell you about mine, in the hope that it makes you feel like you're not the only one out who has been through this! (Sometimes I felt like I was some kind of freak and that made it a whole lot worse).
There was no other woman, or anything approaching that in our case. The reason for the freak out was anxiety, caused by a combination of factors: being torn between me and the PIL who are status-obsessed (I am working class and not good enough, he had always done their bidding before), a high stress job with lots of pressure, and the whole awful experience of wedding planning with my family, who are highly dysfunctional and abusive.
His uncertainty lasted literally two days, then he wanted to get back together. We did end up getting married, but not until some years later, and certainly not before DH had been through LOTS of therapy and had exhibited extreme contrition for years.
I thought about staying with him very, very carefully. I am by no means a doormat, I didn't want to 'settle' for something that wasn't right, and I felt absolutely battered by the whole experience, so I went to a counsellor myself as well. It was only when I felt absolutely comfortable that he was genuinely sorry that I moved back in, and it was only when I was certain that it was some weird kind of a 'blip' that I agreed to get married again.
The wedding was very plain, and had a slight (accidental, unconscious) Jane Eyre theme - that heroine with all her strength and passionate independence and cancelled wedding got me through that time. We put PIL up at the house on which Thornfield Hall was based for accommodation during the wedding weekend. 
I felt like the anxiety was a kind of Bertha Mason locked up in the mental attic, and that it came from them - so it did feel like an exorcism, in a way, to use that house.
I don't think we'd have got through it if we hadn't genuinely loved each other. I'm glad I did it, but it was a long and arduous road and I felt horrible for a very, very long time - upset, angry, confused, you name it. In many ways, I think it would have been much easier psychologically just to break it all off. What I'm trying to say is that even if he changes his mind, it isn't an easy road, and you need to think whether it's really worth it. Of course, right now you wish this had never happened. Right now you just want things back where they were. But you can't 'undo' this. And if you pretend you can, you'll just waste loads of time and energy and be very miserable. Whatever way you go forward, it has to be a new way.
I urge you to reach out to people around you in real life and tell them what has happened. I didn't do this - I went through it privately, and alone - and it was awful. I felt a mistaken sense of humiliation at the time, as if people would think it were somehow my fault it had happened (I couldn't turn to my family, because my Mum was actually rejoicing that she didn't have to travel 300 miles to go to my wedding, because it was a 'hassle' for her. Yes, she's like that). However, when I did open up, I found that people were generous and kind and all shades of supportive. When I told the woman at the wedding venue, for instance, she actually refunded our deposit. Please, please tell friends and family and build a support network. You need people with you in real life!
Sending you 
.