Quote: So, how long is too long to hold on and am I just being foolish to hold on?
You're not being foolish and only you can answer the question about how long you are willing to hold on. I think if you otherwise have got on with your life and are o/w content that you can still hope for and work for a renewed R with your XH.
I think the friendship is a start. Maybe you shouldn't be quite so conveniently available to do the things he needs to have done, but doing some favors for him is probably ok. You know as well as I do that people are deluded when they talk about "never been so in love....love of my life...soulmate" etc. It's just the early infatuation. To me it sounds like it is already starting to wear off of his new love. If he continues to pursue he'll just push her away. You would definitely have a better chance once she's out of the picture if that's what you want. Just live your life, be friends, and enjoy what you have. If your XH later tries to foster the R, so be it. If someone else comes along, so be it. You're in the driver's seat. Live as you would like.
In the end, it's not the years in your life that count. It's the life in your years. Abraham Lincoln
It is hard to fail, but it is worse never to have tried to succeed. Theodore Roosevelt