http://www.stevepavlina.com/blog/200...tor-or-a-cage/
That's the best one I've found. There are others but that hits the nail head on.
As for their opinions. Acknowledge them, let the other person have them, don't dismiss or refuse them point blank, weigh them up for merit and if they have none, dump them. It does sound like you are getting a bunch of well meaning advice from a bunch of fearful people though, so it will be rather polluted.
I think the reason why you feel weird is that you know they mean well for you, but the advice they give is totally at odds with it. It's because the advice says more about them than it does about you. Let them have their advice, take from it what you will and thank them for spending the time to give it.
Lastly, don't get attached to your venture. You can work on it 100% and put everything you can into it, just don't identify with it. If you don't invest your sense of self into it you won't have to defend it whenever anyone says anything bad about it. This will prevent you from having to defend it from the bad advice and just take everything as it comes. It means you don't have to act on the bad advice, you can just let it be.
I hope this helps you somewhat.