Pact with my Sister

Ok - so my sister and I are signed up on the same dating site. We made a pact that no guy would ever come between us, so if one of us has already met a guy and then that same guy messages the other one, he is off limits. Well, I found out today that one of the guys that I have been talking to for a couple of days has actually already met my sister! And been to my house! Once I found this out and mentioned it to him, things got interesting. He kept going on about how they did not do anything (this I already knew, I mean, C'mon! we're sisters!) and really wanted to meet me. Explaining to him that it would not be happening was a chore. Sorry guys, my sister is family and nothing is coming in between that!