Don't be too put down by this. I haven't even read your story, but I will guess that your story did suck at least a little or probably a lot.
That's fine. Honestly.
To tell you the truth, of course your first story is going to suck, all of our first works are as hideous as a Shoggoth in a diaper slurping a cat's bladder. My first story I've ever written got shit on by my Dutch teacher. He told me the story had the most blandest and most boring protagonist he had ever read. It was honestly quite embarrassing, but he did gave me some great feedback. If that person, you were talking about, gave you some real advice on how to improve your story, just take it! If he just said it was just bad, then it is a great opportunity to learn how to grow a thicker skin. Even if you did wrote a masterpiece, not everyone is going to like it. Hell, I still think Louis Couperus' works are the most boring, infuriating schlock I've ever read, even though he is my old teacher 's favourite author. Even if some of these people on the site are a little harsh, one thing (I hope) that they have in common is that they are all passionate about writing and always want to see more great stories being published here.
So I'll advice you to make more crap, make every single rotten thing you can think of, experiment as much as you like. If it's that terrible, take the feedback, then take it down, archive it and write more and more garbage till your work is on par with the site's standard and hopefully more readable. The only way to make a gem is to delve out a bunch of excrement. So don't be afraid to continue.
However, I will advice you to maybe take your work first through the writer's workshop section before you publish it. You can post a link of your story in your post and let other people take a look. it'll probably save some headaches and you'll also get some great advice from other people on how to improve your writing skills.