I wouldn't call her and be "busy" in a way like Frozen Heart suggests if she calls you and eventually she'll probably get the message.

Friendships are hard work and both people have to want to work at them and if you don't wish to invest your time and effort with a particular person, that doesn't mean there's something bad about or wrong with you!

I think it's natural to be resentful or jealous if someone else gets more attention consistently or talks too much about themselves or their affairs and never quite gets around to letting you talk about yours or listening, if you do get to talk. I have nieces and nephews and use to be jealous of them because my stepmother would treat them (her natural grandchildren) "better" than she had treated me growing up, they were allowed to do things I had not been, etc. It sounds like this friend just hits some of your buttons and isn't a good match for you to want to be friends at this time.

Too, you could be honest with her, have a conversation where you tell her you're having personal problems and don't feel you can be a good friend to her at this time. If you keep what you say to "I" statements instead of anything about her (such as her crossing the very clear boundary you expressed to her) it is less likely you will feel badly and that she will be hurt. If you are talking about yourself and problems you're having she can only be hurt by twisting what you say and making it about herself, something you can't do anything about.