this guy that i`ve known for a while has asked me out. we really didn`t ever talk because he was quiet and shy. and now that we`re in most of the same classes, we talk. I didn't really answer his question... but his sister's friend(his ex) found out and took me aside to talk about my situation. She told me that she treated her badly when they went out and that i shouldn't go out with him. but i've heard from this other girl that he`s a nice guy and he`s really sweet. and i don`t know what to do anymore these two girls confused me..

Talk to him about it.
Because his ex may just as well be jealous, but then again she could be telling the truth.

and the other chick may only know just one side of him

and since hes shy, you never REALLY know because he could be hiding something.

I agree with the above. Talk to him about it. Especially if you don't know whose telling the truth. The ex is either jealous or she doesn't want you to get hurt like she did. So yeah, talk to him.

his ex might not be over him yet

if you like him just go for it and find our for yourself.

walk up to him and do sumtin about it!!!!

^^ i agree with her, i mean his ex MIGHT be jealous and yet telling the truth..
so i think you should actually go and get to know him better prolly as a friend or sth.

but then he's shy, so he might not open up to you alot, but then again you guys have known each other for a long time

yeah...my current bf is shy too, you have to "hint" stuff and hopefully he'll catch the drift and do w/e you want yeah...mine took a while