Perna! I totally did that with my worst recurring nightmare in therapy. Together - she let me- turn him into a boggart and come out of the wardrobe and my adult self (as lupin) helped my child self raise the wand and say Ridckuls and make him turn into something - well, not laughable, but something my childself felt she could handle. And POOF he went up into smoke and i can honestly say i've not had that nightmare since- it's been well over 2 years.
kiya