If she is coming by that much as you suspect she isn't over you. That much is not a coincidence. You should be as indifferent as possible because that proves to her that you don't have the same feelings. She needs to focus on her relationship. You should also be direct and firm with her letting her know that you don't enjoy her visits. Avoid any contact that you possibly can because that sends a message as well. I would if possible say to her that you are not interested and would hope that she would move on so that everyone is happy once and for all. She may take some convincing but the combination of directness and indifference has to continue until she gets it. Keep ignoring her as much as possible and eventually she will move on (it's just taking her longer than necessary).
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Thanks for bringing your question to JustAnswer.
Based on the information you provided, this person is trying to get revenge by causing problems in your marriage. She knew your wife would see her trying to make eye contact and being really loud about "there you are" as you were leaving.
She is trying to cause trouble to make up for you choosing your wife. This type of person will break up a marriage, keep the guy for a month or two, and then cheat on him. You said yourself she's the type of person who enjoys making others suffer. Stay far away--this woman is trouble.