A friend told me a few days ago: "you don't realize how much unhappy, miserable and asphyxiated you really are in a toxic relationship until it is finally over..."
Sara, you are a warrior, thinking already about your professional future is the proof that you are on the right path. It's ok to have those overwhelming feelings because you had been forced to turn the page on something you fought so much to save, allow yourself some time to express them.
Take the time to heal, to laugh, to be silly and even make fun of what you went though, yes you can... my H hates my funny jokes/references about his endeavors but I also joke about what I went though with my closest friends, it can be pretty hilarious. Having a good sense of humor was a lifesaver, at least for me plus a few good friends.
Now, another thing cross my mind, make sure to keep your kids' passports with you. Nothing wrong with being careful.
Keep track of his "time" with the kids during the week and the week end.
Kids are resilient if given the right support even by only one parent. I witnessed that not only with my kids but also with others, it takes time but with love and the right guidance they strive. The road might be very rocky sometimes (a lot at the beginning...) but keep your eyes on the finish line. Life is a journey filled with a few tornadoes, hurricanes, rainy and sunny days.
He is the one who failed you and your kids not you. So stop blaming yourself for whatever you might have in mind and turn your gaze to the present and the future.
Me 52+ WH 57+ Married 20 + Piecing since 2016 (ready to give up...)