Hmm, that seems like a tought situation. It seems like you've already tried just giving her space and doing it gradually from what you said. If she won't leave you alone, maybe you could try to talk to her? Nicely, not like, rudely or anything (although I don't think you'd do that
) maybe try and tell her that you guys just need a little space? Not saying you don't want to be friends, but that you're starting to make some new ones and would like to spend some time with them, stuff like that. That would probably make it easier to just gradually let her in on the fact that you're not really as close as you used to be.
I hope that helped! Sometimes I feel like I'm the only one who understands half the things I say