>>81661591 (OP)I think you can stop talking to her for whatever reason. If your parents set you up with her then I think you owe her the same explanation you give your parents.You have a valid reason for ending contact, but if you had any kind of relationship with her then you owe her at least some explanation.
I don't know the details, does she know you have romantic intentions? Does she actually have romantic intentions for this guy or is he just some new friend of hers and you're jealous? I think the grown up thing to do is talk to her and lay the cards out on the table. After you've communicated your feelings to her you don't owe her anything else.