How should i responce to my gambler uncle,since he using some hurtful word to insult me like saying i am a...?

Goodness, those words are very harsh and hurtful. What kind of an uncle you have. Eventhough you must have been very hurt by this, responding further to your uncle is of no use. Since he was able to hurl such words at his own nephew, he would surely do the same thing again if you confront or response to him. I know this is hard for you but the best thing you could do is to ignore him. There is just no point to deal with such people. Continue to do so will only make you hurt more and more. So ignore him and let time heals your wounds.