What to do when a women who is attracted to my man flirts with him in front of me?

We are going to a huge Christmas party this weekend at a friend of mines house who is extremely rich. Its always a huge deal with lots of people, lots of food, and entertainment. My friends sister in law who is obviously attracted to my man is always there. We have been around her on plenty of occasions and she is always trying to make long conversations with my b.f. and leave me out. She will sit there and talk to him all night if she can. I know he isnt attracted to her , but he does like her as a friend. She is definitely attracted to him has made it more than obvious. I dont mind them talking for awhile because I trust him, but the point is he is my date. We dont get out together very often and I want him to spend time with me not her. She trys trapping him in conversation everytime we see her and Im left by myself mingling. She never brings a date. It gets to the point where if you didnt know us you would think they were together not us. I've already told my b.f. a simple how are you doing is fine , but he is my date and he will not be engaging in conversation with her all night. I've seen him back off when she trys moving closer even make an excuse to remove himself from the situation, but she always comes back and will sit right next to him. I dont want to make a seen she is my best friends sister in law, how can I make her feel uncomfortable when she starts her bullshit again without making it seem as if I'm jealous of her? My boyfriend doesnt seem to think theres anything wrong with sitting and talking to her because hes not attracted to her. I just want them both to understand it makes me feel left out(I'm sure thats what shes trying to do) and since we dont get out that often I want him to spend time with me!!!! Any advice will help Thank You I appreciate it. Should I go up and start kissing him or something because I know the situation will arise again it does everytime!!!!What to do when a women who is attracted to my man flirts with him in front of me?
slap her, punch her, dump her, and humiliate her!What to do when a women who is attracted to my man flirts with him in front of me?
Well ill tell you what worked for a friend of mine. She would have her boyfriend start up a conversation with somebody else and then she would start talking to her boyfriends semi stalker about other men and how cute they were and focus he attention on that mainly famous men but a few that might be in the room. Of course her boyfriend knew what she was up too and it defused the situation quietly. Maybe you could try this. Its not violent or confrontational.