Weaning is such a hard time for all involved! The emotional and physical changes throw many of us for a loop!
The decision to nurse her tonight is yours, and that time may already be past, since I'm a few hours past your post. There's no perfect answer, you have to do what feels right to you (and her!).
As for the longterm weaning, you can't force her to nurse. If she still wants to, she will. Weaning an older baby/toddler is often a gradual process, with fits and starts, changes in pattern and routine, and unexplainable increases and decreases in nursing frequency. Weaning is rarely a smooth, gradual curve. Rarely does a mother think "gosh, I wish I hadn't nursed her that one last time", but often, mothers think "gosh, I wish she wasn't weaned already!".
The emotions you describe about the choices other mothers make are normal. Some of us recognize ourselves in them, and how our life may be different had we made slightly different choices. It can also be a reflection of your personal feelings about nursing, weaning, and childrearing in general. It's ok to feel sad about it. If it really starts to get to you, try repeating to yourself "It's not my baby" over and over til you get distracted by the beauty that is your own child.
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