How do you handle being around someone you cannot stand?

How do you handle being around someone who you just really detest? There is a woman who is a former friend of mine---former b/c I entrusted her with a deep, emotional issue I was having, she promised not to tell, and then of course she did. She is one of those very self-righteous, holier-than-thou people who fancies herself as perfect and loves to gossip about others, but I didn't know this until it was too late. She has three daughters exactly like herself, the oldest of which is the same age as my oldest daughter. They are in school together and my daughter cannot stand HER daughter, either. We have to see them at church every week of all places, and other than changing churches (which isn't an option), I don't know how to handle this. I feel like I cannot even be comfortable in my own church. This person even once told me she was sorry I attended HER church (after I had disclosed my issue). Needless to say, I'm having a hard time with forgiveness.