Relationship work – choosing someone you do not wish to develop a relationship with?

Hi! I have just started Scholars and wondering whether I should choose my husband’s ex wife as one of my relationships. I don’t have much contact with her and don’t wish to engage further with her, other than the strict minimum, but every time I talk to her (or have to listen to her) it shakes me up so badly, sometimes to the point of rage, tears and feeling powerless, that I feel that she would be a good choice after all. I am scared of having to experience these strong emotions though, and scared of her obviously.