Oh, I get it now.
It's not great. Sorry you have all that going on!! I guess if Willow is so teed off at her own reflection, she won't want a friend.

I'm glad you have her, so you can have some therapy!
I don't have any dog calming secrets for you, wish I did! I hope in time the two dogs will bond enough to satisfy the anxious one! One of mine gets uncomfortable when I leave the house at an abnormal time, especially if I'm in a hurry (read late to dentist, etc). If I don't prepare her well enough she will poop on the floor in the time it takes me to go to the car and come back for my wallet.
The best chance I have, besides ensuring she has pooped already, is to observe all the standard leaving procedures 30-45 minutes in advance of leaving, including loading the car with anything I have to take with me. For me, that means putting on shoes, carrying keys, taking them out back to pee, putting them in the bedroom with the baby gate. I have read that it may help to make standard leaving procedures (such as walking around with your purse or keys, or in my case, wearing shoes) a bigger part of your non-leaving lifestyle, so the dog can not take all these things as cues to get worked up.
It might be worth a try, as well as practicing leaving for increasingly greater durations, starting with just going out, closing the door and coming back. If you want me to check my dog books for where I found instructions for that, let me know.
-MissK