I think the biggest issue here is why, after all she's done to you and others, you'd still think she's worth pursuing.
If I told you that I was in love with a woman who is cheating on her husband to be with me and was also sleeping other men besides me, was lying to her family and was going from door to door preaching the Bible to people the whole time, you'd think I was crazy. You'd wonder why I was being so pathetic.
You say you feel guilty and would like to apologize to her husband and are worried about what you might say when you see her again especially if she is with her family members lest you her into trouble with her church. I think the reality is that on some level you hope this is exactly what happens so that you can (understandably) get back at her for what she's done to you. If you truly felt guilty about this relationship, you'd want nothing more to do with her. You'd be thanking your lucky stars that you were free of this horrible person. It's as simple as that.
You need to talk to a professional about this and find out why your self worth is so low that you'd allow yourself to be treated this way and to find out why you'd want to continue a relationship with someone who is so dishonest and mixed up.