To me, a friend is a friend, regardless of their past. We all had some hardships in our pasts... and some of us had done so terrible things too. But, I'm always more interested in the present and the future! :-D
This shocks some, who do relay their pasts to me. But should it really? I mean, they don't care about my tragic past, of the many times I tried to take my own life. So, why should I let their past stop me for being a friend to them also? That's just silly! =p
Live and let live!