Hugs to you PL.
I can hear your pain. I am so sorry this is happening.
I wish I had some good advice for you. I , like you, tend to plan my future events with STBX in them. Wishful thinking. We always had such great times together when we travelled. It nearly killed me when I found out that he want skiing with OW over Christmas. He has never been skiing without me. I have stopped asking the question,"How can he -------(fill in the blanks) and have realized it doesn't matter how can he, but just that he can.
Take GOOD care of yourself while he is gone, I'll say a prayer tonight for you.