I'm trying to distance myself from one of my friends because of my feelings for her
That's smart. What kind of feelings are you having for them?
Because I care about her welfare, I just want the best things to happen to her.
It's good to care about what you think is best for a friend. If you distance yourself from them however they may feel like they're losing a friend. Try being honest instead so you don't make them feel like they're being ignored.
It's not easy to hurt someone you like.
If you don't want to hurt your friend then try being up front. They'll be more hurt if you intentionally stop being their friend. Good intentions doesn't always mean no hurt feelings.