I know this proof is somewhat similar, or related to the Baire's Category Theorem but I can't seem to figure out how to do it.
The Baire Category theorem asserts that if X is a complete metric space or a locally compact Hausdorff space (my case), then the complement of a countable union of nowhere dense sets is always nonempty.
How can I use this on the proof?
Since every compact Hausdorff space is locally compact, you can actually use the statement that you mentioned.