[Objective]

Rawn: Send a text to your sis then and say you want to talk cuz you're conflicted. Then perhaps you can learn more about the chick as well and how serious she is (if she isn't all that serious, then fuck.. Just go for it) and how your sister gon' take it etc. Just say that you don't know how you feel and wethere you want to give it a shot or not. All that shit.

Your sis will probably say some shit like ''just see her and see how it goes'' or something. Given what you've said to her you can meet up with her, bang the chick and politely decline if you have no further interest in seeing this chick. Just be honest about it that you don't know what you're feeling. At least that way she can't whine and complain that you were just another asshole cuz you were real about the situation all the way from the start. Leaves you with more options as well.