I'm not really sure if this is the right place to ask for help but whatever, it might help me sort through my thoughts. I've never had a problem like this before.

About a year ago, this friend Bob [m25] met up with me [f24] at a bar so we could catch up and chat. We were good friends back in high school but fell out of touch through out the years. I heard a rumor that he was dating my friend's sister, Julie. (We'll call the friend Amanda.) When I asked him about it, he went on a strange rant about how she broke up with him among other details I can't remember but couldn't really make sense of. 

The following weeks after I was told by Amanda that Bob raped Julie. As far as I know the police were not involved, hence no prosecution nor evidence collection. So it's really been reduced to his word against hers. I don't really know the full story, nor do I understand what really happened between the two. Now a year later, he wants to hang out and build up our friendship again. 

I don't want to continue the friendship because I feel as though it would show that I don't support Amanda and Julie and their family. BUT I don't want to have to say, "Look Bob, you're a rapist. I can't be seen with you." Since I don't know the whole story, I feel I would be the one "casting the first stone."

I'm a terrible liar and I'm bad at confrontation. What can I say to him that indicates I won't hang out with him but won't stir up trouble? 

EDIT:
user
Friend is a suspected
assistant
I'm not really sure if this is the right place to ask for help but whatever, it might help me sort through my thoughts. I've never had a problem like this before.

About a year ago, this friend Bob [m25] met up with me [f24] at a bar so we could catch up and chat. We were good friends back in high school but fell out of touch through out the years. I heard a rumor that he was dating my friend's sister, Julie. (We'll call the friend Amanda.) When I asked him about it, he went on a strange rant about how she broke up with him among other details I can't remember but couldn't really make sense of. 

The following weeks after I was told by Amanda that Bob raped Julie. As far as I know the police were not involved, hence no prosecution nor evidence collection. So it's really been reduced to his word against hers. I don't really know the full story, nor do I understand what really happened between the two. Now a year later, he wants to hang out and build up our friendship again. 

I don't want to continue the friendship because I feel as though it would show that I don't support Amanda and Julie and their family. BUT I don't want to have to say, "Look Bob, you're a rapist. I can't be seen with you." Since I don't know the whole story, I feel I would be the one "casting the first stone."

I'm a terrible liar and I'm bad at confrontation. What can I say to him that indicates I won't hang out with him but won't stir up trouble? 

EDIT:
user
A friend of mine
assistant