How can you break up with your sisters boyfriend?

Answer 1

You chose to create this huge mess, and by doing so, to accept any and all consequences related to it. Want to end the affair you're having? End it now---bluntly, firmly and have no contact or as limited contact (only in public) with this man as you can. The minute you start chatting with him, taking his secret phone calls, texts, you'll find yourself drawn back into this affair. However, while you want to keep this affair from your sister, you can't guarantee that at some point it won't come out---either via her boyfriend out for revenge, a family member or someone else. And finding out about her boyfriend's affair will be less devastating than when she finds out it was her own sister he was cheating with. Your relationship with her will be damaged; not only because you cheated with him but you betrayed her trust, you continued to hide the affair in order to save your own a$$, allowing her to continue to date a scuzzbag like her boyfriend. She'll be upset and hate you now if you confess the affair to her, but she'll hate you even more if she ends up marrying and having children with this loser, only to find out then what you and he did. So you chose to deal with all the consequences, and this is your chance to do the selfless thing and stop saving your own skin. So deal.