I would refuse to be around her alone and I would not feel it were necessary to explain why I would just be busy. I would just stop answering her calls and texts unless it's regarding work at work. I would treat her like an acquaintance or casual work friend. If you have someone trusted at work who has to go to the same meetings as you or in your group that could run interference for you such that you don't have to sit next to her or who could come to your rescue if you get cornered.

Perhaps you could get her angry at you about non work stuff so she will leave you alone...like if she complains about her H to you then you could take her Hs side... Or better yet introduce her to your least favorite person that she would have a lot in common with and perhaps they will hit it off and leave you alone.