@Big Col,
Big Col, it's not something you did wrong or could have done more or better -
you did all you could, but her heart was not in it, and as sad as it is, she should not have had a relationship with you while she was still emotionally tied to her dead husband. She needed you and used you as rebound relationship. It is very unfortunate for you as you came into the relationship
from a different angle, but reality is what it is.
What if you enter into another relationship in order to lick your wounds that help you forget about this women you still love. A few years down the road you know that you're over the hurtful relationship but you're stuck with a new relationship that was built solely on helping you get over another woman. Suddenly you notice that this new relationship is based under false pretense and that it has run its course. You were so preoccupied with getting over your old love, you never spent enough time with your new relationship and now it's too late. You're not emotionally vested and you
are ending the relationship. Surely, it wasn't fair to the new woman, and
it's not her fault at all, but she happened to be there when you needed someone to bridge over the emotional tie from one person to another.
Do you see now that you were the "emotional bridge" to this woman?
You helped her overcome the death of her husband and helped her to enter a new relationship. You did an outstanding job, the only problem was that
she wasn't emotionally vested in you - she had to overcome different emotions.
You did well, but you did not have a relationship that was built on equal
terms. It's very unfortunate for you, but it is what it is - reality!