Hi.
My husband brought this up to me about a years ago. The word "never" came out of my mouth a few times since then. We had one MFM, well, one confirmed and 2 unconfirmed. [Thats another thread]
The most important thing is not to push the issue. You brought it up, even to the extent of a letter. Now, leave it alone. I know how your wife feels. There are many questions going threw her head right now. Maybe send her a link to this site. I know it has helped me out a lot. After that, I wouldnt mention it again. Start focusing on her and your relationship. When she is ready, she will let you know. Also, if she does bring it up, dont get all excited about it. When she drops the issue again, be sure you do too.
It's a long road to travel for some, just ask my husband!
The Mrs.