Throughout the play, George and Martha spar viciously with one another and with their guests. It is unrelenting, but Martha has makes one mistake: she mentions their son to someone else, thus opening up the secret fantasy that has kept their marriage going. The "apple of our eyes...Martha being a Cyclops" is another game (but it is a very private game with their "son" bearing a disquieting similarity to George's youth) between George and Martha and she has made it public. The ensuing brawl ends with George's decision to put an end to the fantasy and, perhaps, an end to all of the games. But in order to do that, he has to "kill" their son. When Martha screams at him that "You can't do that!" his replies "Of course I can. We just never talked about it" revealing that their games - which have become their life together - have always been held together by a mutual complicity in maintaining the fantasy. Remember, "Who's Afraid of Viriginia Woolf?" is a love story. But George is exhausted by a love that requires such artifice. By killing their "son", he puts something even more challenging to Martha: to love one another as they are - with all of their disappointments and failures in themselves and with one another - without the "comfort" of lies and fantasy. And it is that fear - to be seen and loved by George as she is, not as she would pretend to be - that frightens Martha.
The final words in the play are uttered by Martha who says simply, "I am" in response to George's singing to the tune of "Who's Afraid of the Big, Bad Wolf" altering the words big and bad for the name Virginia. This sums up the essence of the play. Martha must live a life of illusions in order to survive. In order for George to survive he must also keep these illusions alive even though it makes him miserable. In the end, tired of it all George hauntingly but somewhat lovingly sings the tune to which Martha responds. Through out the play there are ups and downs in the illusion of their having a perfect wonderful son is explored and at points, the reader does not know which way it will end up. Will they both exhaust the fantasy and give up the illusion which is ultimately not keeping them sane and together but driving them apart or will they continue to live the illusion? In the end, Martha's fear of letting the illusion go is revealed in her last statement.
Martha is afraid of Virginia Woolf - George, Nick, and Honey are not necessarily afraid of Virginia Woolf, just tired of dealing with Martha's behaviours due to her unsubstantiated fear - absurd - illusionary, and maybe deluded - alcohol abuse must be considered as a factor in Martha's behaviours.
Virginia Woolf is a very intellectual author - a pioneer of the literary term and device referred to as stream of consciousness. The author has license to enter into the characters thoughts and reveal them to the reader/audience.
For whatever reason - existentialism/absurdity, Martha is afraid of Virginia Woolf. As anyone with a borderline personality disorder does so does Martha draw attention to herself in anyway that she can - an imaginary son - George exorcises her illusion... does he - probably not but he does by tolerating Martha's belief purge the pent-up emotions of Nick and Honey when they reveal that they are unhappy because they were married for reasons other than true love.
So, when George asks Martha who is afraid of Virginia Woolf and Martha says that she is - the game will continue.
You mean - who's afraid of the big-bad-wolf... all are afraid of the BBB,and Martha, George, Nick, and Honey are afraid of Viginia Woolf, too because Virginia Woolf has entered into their stream of consciousness - they act absurdly - the antithesis of what is expected of an intellectual party of four in the land of capricious consumption. George and Martha are stripped naked - so to say: rhetorically while their guest's Nick and Honey worry if Martha's invitation was meant at such a late hour.
Back to the last sentence - Albee wrote an existential plot about what if four intellectual people acted as if they were not afraid to reveal their true or what may seem true feelings instead of acting behind a facade of [peach fuzz] as they are expected in the social circle of which they are a part. Nick and Honey are eventually drawn into this absurdity and purged of the emotions that Martha and George portend - afraid of Virginia Woolf.