what is the sexuality called where

What is the sexuality called when you are in a marriage with the opposite sex but are attracted to the same sex (a girl who's married to a man but also attractited to women) but could never marry a women?? 
Sooo confused!! Please answer. I posted in CC because strangely, I feel like you'd all know the answers as this is a passionate topic. I wouldn't call it bisexual because if they couldn't actually be with a women wouldn't it be called something else? Or no name? Thanks