In time, when you heal, you will remember the good times, and it will not hurt as much.
Fib, I think it's time for you to stop rehashing what has happened. You know you did the best you could. You know she didnt. And in order for you to really move forward, you have to let it go.
So, take what you've learned on this journey and begin your new life. Start new traditions with your children, explore new possibilities and leave yourself open to accept what life offers.