There is a sea of fiction out there. No matter what you write, someone else is writing it, or has already written it, or is planning on writing it. Vampires. Fairies. Private Detective Vampire Faeries from an alternate earth, chasing an angel who framed them for the murder of the King of Goblinland. Paranormal romance. Epic fantasy. I could go on.
The point is, all of this stuff is out there- and there you sit, smiling over the finished product that is the end result of weeks, months, or years of your time. It has been the most important part of your life for all the time you've been working on it. You obsessed over it. You lost sleep over it. Hell, maybe you're like me and your writing was a contributing factor in the end of a marriage. You bled for your Urban Dark Fantasy where the only item that can destroy the Dark Lord is a shard of unicorn horn, and the very last unicorn is dying (just an off-the-cuff example, not the plot of my own novel).
And now? Well, it turns out that yours is only one of a million messages in bottles drifting in the sea of fiction. No one really cares. It's sort of like thinking that your baby is the cutest, smartest, most precious child in all of existence. The other guy thinks the same thing about his. EVERYBODY thinks exactly the same thing.
So what to do?
Keep swimming, that's what. You used to sit down every day at your keyboard, or your typewriter, or with your pen and paper to write that epic story trapped in your head. Now that's finished, you have to get out there every day and let it be known that YOU have created something worthwhile. You have told a tale worth reading. And you cannot let any setbacks or roadblocks stop you. It's not a question of sinking or swimming- it's a matter of building yourself a raft out of the shattered remains of the ship that was your fantasy and floating on top of that foaming sea.
If you want to catch a break, you have to put your hand out. Someone will take it. And if no one grabs you today, you have to do it again tomorrow.