Hi all. Just wanted to say thanks again for all the helpful advice. As hard as I'm going to try I don't feel very confident in things working out well. I'm almost at a point where I want to simply ask her not to see him ever again, and for them to go back to being old friends that occasionally write letters to each other. There's too much that I know for a fact she's not telling me about their relationship, I've given her every chance imaginable for her to come clean and she hasn't. I even told her that there's zero chance in my allowing their relationship to continue without her telling me everything.
It just sucks all around. She still says she'll never leave me for him. I just am not looking forward to the depression and resentment that will take place if things don't work out her way. But like you've all said, I can't go along with something if I'm not truly invested in it.