I'd say goodby and good riddance. Take care of yourself. Try something new, spend time with reliable trusted friends and family... probably not your sister. Get a dog, get a cat. Volunteer, plant a garden, take a yoga class, keep busy. Do not sit around feeling sorry for yourself. You're better off by yourself than with someone who can create an imaginary life with a fictional person he doesn't even "know" on Facebook!
When he shows up back on your doorstep you can reassess but you might find he doesn't look so appealing after dumping you for an illusion.
"If the world were a logical place, men would ride side saddle." Rita Mae Brown