I know from personal experience there is very little I can say that will ease your emotional reactions. My heart goes out to you and your children. It can help to vent anger by crushing empty boxes.
I second everything Rose76 said. I also suggest contacting a financial planner to help you devise a sound financial plan for post divorce. If you are employed, tell your boss what is happening (basics, not details) in the event you need to deal with something during your work hours such as a call to your attorney, a wave of emotion, etc. Have a chat with your kids guidance counselor so they can keep an eye on changes you may not notice.
Make a list of all your marital assets including retirement accounts, life insurance policies, even a list of tools in the garage. Document everything he takes from your home/marriage in a journal. Everything that was acquired in the last 30 years is a marital asset. Everything he removes from your home, even things you don't want or are 'his' have a value. That awful recliner he insisted on buying that he wants in his new life, counts toward his half of the marital assets. My ex took 'his' boat and 'his' fishing poles. He was surprised that I got to keep all the cash in our joint accounts as an offset to those assets.
I know it doesn't seem like it right now, but you will get through this. Someone told me that the best revenge on a cheating spouse is to be happier without them than you ever could have been with them. I wish the happiest life for you and your kids.
Oh and get to your Dr for a full std screening. Worth the peace of mind because people who cheat and the people they cheat with may not be honest about things..