Hi Kate,
Just wanted to send you some support and let you know that I am another that came out the other side. My 'adventure' was many years ago now and luckily there were no children involved, but my husband up and left me also. We had just moved to a new city and he decided he didn't like it there, didn't like me either, and went home to Mum and Dad. This involved a plane ride and he let slip a week before he left that he was going (had already booked the flight without telling me). I took the week off work to try and talk to him about things. We had a fabulous week together! We spent all our time together, did some fun stuff, lots of chats, I felt really hopeful. And then the day of the flight arrived, he kissed me goodbye and left. I waited and waited to hear from him, and 2 days later I couldn't stand it anymore so I called, his voice was just flat on the phone, said he didn't love me and wasn't coming back. His Mum and Dad just pretended like nothing had happened, didn't talk to me and let him just do whatever he wanted.
Not going to lie here, I more or less fell apart. I was in a new city and knew nobody. I called my parents every night just for someone to talk to, but they were also a plane ride away. I cried buckets. I kept up my daily routine but I was a mess. I tried a few times to talk to him again but it would just end up upsetting me more and I realized that for my own good, I needed to stay away from him. Eventually it got easier. It's now about 15 years later and I have a new DH and 4 DC. And I am in contact with the ex-DH, I guess we could actually be called friends now! He is exactly the same as when I was married to him, doing all the same things as he was then. If I had stayed with him, I wouldn't have my DC and I wouldn't have the very satisfying life I have now. He is on his own.
As others have said, the most important thing to do right now is focus on yourself and your DC. Look after yourself and be gentle. Make a life for the two of you that doesn't require him. Do things for yourself that make you feel good. Make the effort to cook yourself a nice meal rather than just picking at things. Exercise can work wonders! Don't think about the future too much, just cope with one day at a time.
There's every chance that he will come back, but in the meantime, build
yourself a foundation that makes you stronger.
Looking back now, my exDH did me a favour. I learned (the very hard way) that I could stand on my own and look after myself and didn't need to lean on anyone else. That's very empowering!
I wish you all the luck in the world.