I can actually speak from first hand experience and the other side of things LOL My BEST FRIEND in the whole world is a guy! 4 years ago when FI and i started dating i told him about my best friend and explained our relationship (no secrets!) I love him dearly and would do anything for him and him for me HOWEVER I have to take my Fi's feelings in to consideration. When i was single my bf and I would watch movies and cuddle at home and spend endless hours together (nothing sexual ever BTW) everyone always told me that bf must be in love with me but i never saw him that way. THe MINUTE Fi and I started to get serious i told my bf that things had to change. I would always love him and be there for him but there could be no more cuddles, i love you's (except in a birthday or xmas card) and that our friendship would have to take into consideration new boundaries of how my FI may or may not feel about certain situations. My biggest thing, "how would i feel if the roles were reversed" i ALWAYS take my FI's feelings into consideration and so did my BF, he had No problems with this what so ever and completely respected me, my choice and my FI. My point is, if this girl had no "evil" intentions she would respect you and her so called BF and back off. You can still have chats, texts, emails but not in the same tone, not at 4am and certainly no alone time for extended periods of time. Its more then obvious she was trying to be a home wrecker and I am super happy your FI backed off and respected you enough to show you that YOU are more important then her. That says a lot. The unfortunate part is that she will never change, she will always want to win him over and be jealous, possibly even if she finds a guy of her own so you are best to keep her at a distance! Its not easy to change the tone of a relationship, my bf and I had to find new things to enjoy together and new ways to communicate and spend time together but still be friends and not hurt or make anyone worry. If i ever even thought for a minute that my FI was concerned or it was bugging him I would change anything to keep him happy since he is my forever! Keep communicating with your FI and if there are any situations that bug you PLEASE dont even hesitate telling him. You dont want to live the rest of your life with this in the back of your mind and the "what ifs" or always wondering what is going on if FI goes anywhere and she may be around. Thats not a good way to live and not a good way to start a marriage. Personally, if i were you and things continue to get worse, i would ask FI to talk to her and explain how he feels because sometimes putting someone who has unrelaistic illusions in their head on ignore may not be sending the right message. She is obviously dense that she isnt realizing what she is doing is wrong so who says she isnt dense enough to realize that her being ignored means she should go away?! She needs to be told out-right to back off. And if Fi isnt comfortable doing it maybe you need to ask him if you (together) can write her a polite email telling her how you both feel. Either way, good luck and i hope you can make this situation go away permanently for the sake of your sanity and your future marriage