I know how you feel. I had to move countries and (obviously) change jobs right after BD - so I had the hat-trick of life's "most stressful experiences". My XH actually behaved pretty well at the time, all things considered, but that still couldn't make up for the grief, gut-wrenching anxiety, disbelief, outrage at the unfairness of it all and the deep, horrifying fear of the future that I was dealing with. All the while I did what you did - I held it together at work, and I tried to treat my XH with enough civility to avoid nastiness and accusations of bitchiness, craziness and whatever else.
I cried my heart out every night. Sometimes all night. Deep, wrenching, soulful sobs. I lost lots of weight. I think I went a tiny bit mad. However, I made it all look OK on the outside.
I absolutely understand how you feel. It is the worst thing I've ever experienced in my entire life, and I'm sure you feel the same.
Know this. You *are* going to get better. I didn't believe it when people said I would. I thought they had no clue. That they were stronger than me. That they had some special recuperative powers that I somehow missed out on.
I was wrong. They were right. Things did get better - eventually. Don't judge yourself by how long it takes for things to get better. Just know that it will.
You will be so proud of yourself for behaving the way you've decided. You could've chosen a different response, but you didn't. That is all down to the strong, resilient, loving, good woman that you are. Your kids will be proud of you. Your friends. Your colleagues and your family.