I feel a bit sorry for her, but I feel for you too.
I had a 'friend' like that.
She used to call at my house as soon as she dropped her kids at school. I just had one child at the time & she was a great sleeper. So instead of me getting up, I just lay on until whatever time dd woke up at.
Many a morning I would open my curtains to find said 'friend' camping on my driveway waiting on me to wake up.
It started getting bad when she began mouthing off to my husband about not painting our new house...she suggested she go & buy paint & a roller & come down to paint for us.. said she could look after me & dd better than he could! Dh was pissed off with her!
She had a mad boyfriend who started calling me & asking if she was with me 'cos she wasn't answering her calls.... she would tell him she was with me all day even if I hadn't seen her.
Finally she started wanting to take my dd home with her to her house & mind her... I refused saying I didn't like anyone who didn't know dd that well to mind her.. it was madness.
In the end dh had to tell her that I was having a mental breakdown (It's true, I was losing the plot)& was better off alone.
She sent me e-mails for weeks until she must've got fed up with it & stopped.
So I do understand how you feel about friends like that. I don't think you mean you have too many friends & don't need another, I think you mean you don't need a friend with so many expectations of you!