As someone who used to be a writer themselves, back when I was around your age, it makes me truly livid that someone would do that to you. I am so sorry that you experienced that. I agree with Howtoprocrastinate. The more that you write, the better you will get. Never give up on your dreams, no matter how far away they seem to you. Because you never know what good opportunities will arrive when you least expect it.
Also, you probably don't want to hear this right now, but at an attempt to help you feel better, think about how many people bitched about Twilight and Interview with the Vampire, back when they were new; did it stop those authors from writing? Nope. Did it stop the Harry Potter author, or Shakespeare? I could go on, but my point is, they all kept on going, despite the critics. I know it's easier said than done, but try to focus on the good/positive comments that you get on your novels, and don't let people make you question on whether you should continue writing or not. You never know who you could help with your work.
Next time someone upsets you like that about your novels, tell them if they think they can do any better, put their money where their mouth is and go ahead and try.
