I am so sorry things have happened so fast with her decision to leave. Was she open to counseling at all? Really hate it for your children. A split or divorce at any age for a child is traumatic, has she talked to them about this?
Think about what OpenEyes had to say in above post. Does she really think this man would leave his wife for her or does she want to spread her wings some regardless if she's alone?
Agree also that this might be some mid-life phase/crisis. Once she gets out there & is completely alone, weekends and all, she may feel different. You never know how these things will turn out.
Take care of YOU!! Try & find a support system outside of your marriage. Go to counseling on your own to help YOU get thru this so you can make sense of all this in your own mind & heart. Your kids may need counseling to work their way thru this. Based on what you have written here sounds like this isn't about you or something you did or didn't do. If she was dissatisfied with your work schedule being out of town all week she should have said so.
Wishing you all the best & keep posting.