you said in other comments that your bf started to be friends with her, because he wanted to date her, and she rejected him because she wanted to be with her current bf. well, stuff's not so great with her bf now, and suddenly she wants a one-on-one week long beach vacation with your boyfriend.... and your boyfriend planned this vacation behind your back, and decided to go, even though he knew you weren't okay with it. he UNINVITED you, from your own romantic beach getaway vacation, to go with another girl. you will always be in second place in his eyes. her feelings are already more important to him than yours, even though she has been stringing him along for ten years and you have been planning a future with him. at worst, they are fucking right now and he's going to dump you for her after you give them rides home. best case scenario: your boyfriend has a best friend who is a woman that he is attracted to, has no boundaries with, who he prioritizes over you to the point that you were uninvited from your own vacation.