It's ok. Sometimes the timing is just not right. It happened to me too, and even though I have regrets, I know it was not meant to be, and I cannot go back in time to change who I used to be.

You weren't ready, don't beat yourself up.

As long as it doesn't hold you back, I don't see issues keeping this person in your life and having some news every now and then. You have to respect basic boundaries though, and telling her your feelings is clearly a big NO. Especially that you might have been too much inside your head, idealizing what could have happened.

The fact is you were not ready, she might not even have been, and you and her might have wanted different things. Don't hang on to the possibility that something will happen one day. Life your life, enjoy yourself, be happy.