At the moment, it's not too much of an issue... just really really makes me feel stabby when someone calls me "Mrs (her last name - ex's last name)." Um... no. Never call me that again.
It's also weird when I'm calling, say, the school about her and they say, "Last name?" and I have to clarify - mine or hers, because they're different. It's not too bad, just kind of annoying.
I want her to have my last name - she doesn't have a thing to do with her father - but not sure how much time and money that will cost to change it. It might be too much of a hassle.