Sweetie, nothing you said was even remotely offensive, and I appreciate the thoughts. I am fairly sure that she sees what I do, and I know she hurts to think she is causing me pain, even indirectly. It is why - even if my most paranoid thoughts were true, and he actually DID like and want sex with her more - I wouldn't ever want her to leave. I'd just have to learn to cope with the feelings. I don't actually, in my more sane moments, believe that this is true... it *feels* true, but I don't actually believe it to be the case.
It is definitely true that we are dealing with a learning curve, and in some ways the dynamics of my relationship with him have changed... and of course, that's a bit scary, too. Even if I knew it was inevitable, it's still a major change and the reality of it is sometimes overwhelming.
However, she makes it worth it, and so I am working towards understanding myself better and figuring out how to adapt. It's really all I can do, at the end of the day.