What would you do if your boyfriend's twin sister was jealous possessive and manipulative and lying about you telling him you were cheating on him and making up other lies trying to break you up?

This is not your problem at all, but your boyfriend's problem! I went through the same thing with my 2nd husband. We were dating for sometime and we were talking about the future. His sister had been in Australia and she came for a visit and it was the first time she and I had met. My husband and her had been quite close as siblings. His sister and I got along fine while she was visiting, but behind my back she told him not to marry me and even wrote him once back in Australia making him doubt his decision to get married. The long and short of it is, I was ticked off with my boyfriend for not using his own head and listening to her and causing big doubts in our relationship. It almost split us up. Many years later she admitted she was jealous and although she was in Australia she didn't want ANY girl coming between her and her brother. So, you have to have a good blunt talk with that boyfriend of yours and tell him to set things straight with his twin sister or you're going to kick him to the curb. After all, who needs it! When it comes down to the crunch and if he loves you then he'll certainly choose you. If he doesn't, then he doesn't love you and he is weak minded and you've just saved yourself a lot of heartache. Good luck Marcy