As everyone else has also pointed out - this is a very personal decision. I didn't have really strong feelings about it either way. If my children had been younger (the youngest was 16 when the D became final, 12 when dad left), I would have kept his name to save confusion. I run a dance school and it is SO confusing trying to figure out who belongs to who and what to call each person. Easiest to call and say "are you Suzy's Mom?" Now when we register new students we write down more info like first and last names of both parents, who child resides with, who pays for lessons - business details. But I digress.
I have been divorced for 3 years and kept my name. For business, it was easier and less hassle. Then when I saw OW (maggot) using my last name I found it especially bothersome. Considering she had been married for 17 years and kept her maiden name then. SO - I imagine it must make her crazy to know that I kept the name. I am the first, the original "Mrs. K".
I did talk to my kids about it and they did not care. I did decide that if I were to marry again - I would change my name at that time. If not, I am who I am. I did not choose to change - it was thrust upon me. Why should I endure yet another change.
But as a good friend of Karen's - I know how important it was to her to change her name. And for her - it was totally the right decision.