I'm going to date a friend's ex boyfriend.
Aren't you worried about how your friend will react?
Nah, I've done it before. She moved on the other times I did it.
You should at least talk to them first. Something like this can cause big troubles in a friendship.
I'm tired of being her friend anyways.
If you don't want to be friends with her anymore, it's completely fine to end the relationship. I would suggest telling her how you feel though. That way you can both move on and look for other friends.