How long will your trip be, and will you guys be keeping in touch while you're gone?
I can hear your frustration about not getting to do something special the night before you go. Did your H know that you wanted to do something special together?
I remember that the OW works at the airport that you're leaving from tomorrow. Are you going alone to the airport, or is your H going with you? Have you gotten to share with him how you're feeling about having to be in proximity to her? Is he supportive?
I hope you will have a good vacation. Take lots of time for you, and let your family on the other coast love and take care of you. It sounds like you had a good time with your mom this afternoon.Find peace. Or sleep on it.
Infidelities are like icebergs - they may take many different shapes and sizes, but they all damage your ship.