Hi Jan
I am sorry to read your post - it must be very hard for you. You had a double betrayal - and it is really hard to forgive people who do not accept accountability for their behavior. But remember that you are forgiving her for *you* - not necessarily for her.
Then to have the sting of it happening in your own church - where you should feel safe - this is hard. Is she in another congregation now as well? I'd have to say that it may help if you look at her problems as spiritual. It doesn't matter who her husband is or how often she goes to church - she isn't right with the Lord. If she won't call what happened an affair or adultery - do you think she has owned up to her behavior with the Lord? My guess is no. True fruit of the spirit would mean that she accepts accountability - and true repentance would mean that she ask for your forgiveness for her behavior as well. (Not to mention the fact that this happened in the first place – which shows that she wasn’t right with the Lord even then.)
Have you thought about spending your summer in studies? Bible studies are a great way to meet other women - and you might find a new best friend. <img border="0" title="" alt="[Smile]" src="images/icons/smile.gif" /> Digging into the Word will lift your spirits - and it will help you to forgive her. Don't forget that we are told to pray for our enemies (this is more for us than for them I think).
I think that your blues may also stem from your daughter's wedding. Maybe you are thinking about marriage and subconsciously hoping that your daughter doesn't have to go through what you've been through - especially with the connection in the bridal party of the OW's daughter. I think you are well within your rights to ask that she not attend - this is more your day than hers. We are supposed to forgive - but this doesn't mean that she has to be your friend any longer - you don't have to see her and be close to her to forgive her.
Here is a link to a Bible study for broken relationships - such as the one with your friend:
http://www.nacronline.com/dox/library/biblestudies/broken.pdfI hope that some of this helps and I am wishing you well.