Personally... I would reply overly positive to them, like they had just given me kind worded constructive criticism... usually that makes them apologize.
Then I would look at what they were calling trash, they had a reason for saying it, (not saying they actually did in your case) (but if it was ME) i would look into writing workshops. I am still always looking at ways to improve my writing, workshops and lectures are a great resource.
And lastly i would reassure myself that no matter what anyone else believes about your writing, you had the courage and creative mind to start writing. You are trying and giving it your all.
No one can make you feel something or someway unless you let them, so don't let them! <3
AGAIN YOU DON'T HAVE TO DO ANYTHING TO CHANGE YOUR WRITING, THAT PERSON WAS BEING AN A$$