Snowfed,

Had it not been precisely put, I would have thrown your story in an iggy bin. Your story sounds credible enough for my two cents, so here it goes.

Now that you have called it quits, it should not bother you who she communicates with. All your sister needs to do is put receiver down, that will end any further calls from her. What I see here is, since your sister had been entertaining her calls even after that (heart rending?) breakup, you need to settle the score with her than seethe cursing your ex.

Also, either you can ignore or avenge, but being perplexed like you are now will not get you anywhere. If I were you, I would have acted in a way as if she never existed OR simply meet her somewhere and cuss my lungs out, cuss her so bad, it'd scare her angels off. If you cannot do both, you are still in love with her - (snicker) enough to make a big fool out of yourself once again. Bet you are smart enough to make your next move.