You have done the right thing.
I disagree with Merville. I think that many women who want a relationship with someone mistakenly enter a fwb arrangement with a friend, or someone they've only just met which kind of negates the 'f' element of it, in the hope that it will become a relationship. In the hope that the man will realise how much they really like her and that love will grow.
That's the absolute opposite of what a fwb is about. I've had 3 over the past couple of years.
The whole point is that there is no exclusivity, there are no promises about whether the other person is chatting to others, or dating, there is no anxiety and insecurity about it, because there are no feelings involved.
I stopped the 'b' elements of my friendships, but am still really good friends with two of the men. One of them tries on occasion to resume it, but I'm not interested currently and the other, it's like it never happened.
I don't understand this whole "women get emotionally attached after sex" thing. It's never happened for me. It's just sex. But I would absolutely not agree to enter into a fwb situation with someone I wanted more from because that's not what it's about. It's a friendship with extras, not the beginning of a road towards romance.
A proper fwb is as respectful as any friendship. It's not one person using the other for sex. It's someone you trust and enjoy spending time with, as with any other friendship. It's a real friendship. But with someone you sometimes have sex with. If it's not that, it's not a fwb.