Sandy, it's my opinion that you have no need to try not to cry. Grief, unless your parents are extremely self contained and hate the sight of emotion, is both normal and healthy. When March 2 arrives and you see them, and go to their clinic, you will find that the professionals are used to having the extremely upset patients and also their families. You seem to be placing a restriction on your emotional outlet that is very stringent.
Now, I know you have a plan for them to come to you... but your daughters are in denial and your boyfriend isn't expected to help. What do you envision as your mother's caregiver? Are you working part or full time, and will that change if it's the case? Will your dad be doing the bulk of the care with your back-up help?
And, finally, do you have close friends who have already volunteered help in concrete ways? A church perhaps offering help?
I'm not asking to make you feel more fear, but trying to get a grasp of what is already in place or what might happen to help you. Meanwhile, I think that other than do what you can (if anything) to get some help set up, you should give yourself permission to let it out, and believe that there will be professionals at the clinic (an ALSA person--a Social Worker) who will help you in many ways. Contact the ALSA in your own area and let them know you expect your mom and dad. They may offer to come and see what may be done in your home to prepare. And give yourself grace.
Ann xoxo