I'm so sorry you're having to uproot your family just to get decent medical coverage for your son. That really sucks. You have every right to feel down, I sure would. It must be just awful to leave a wonderful home and family to live in a cramped place, even if it is a temporary situation. It DOES suck and you go right ahead and feel the way you feel. No one should have to do what you are doing.
No, it's not forever and yes things will change, but at the moment it's not
changed so you feel sad. Indulge your feelings, don't hide them or ignore them. It's okay if your kids see you sad, you're human. But they will see you be happy again.