Kudos to her for apologising. Sometimes its tough to say your sorry but if someone rejects that apology it can be pretty hurtful.

I would say, accept her apology but don't have any expectations of her. Its our own expectations of a friendship that let us down.

You can be civil to one another without it ever having to go back to what it was. I don't have friends who talk and gossip about other people we know and like. If someone tries that with me I will always say, "wow, how can you say that?; so and so is a really nice person and she thinks the world of you". Spiteful people will not only talk about your other friends to you but about you to them when your not around. Stopping them doing it is very satisfying.

Also think on, she's like she is because she basically has problems and if her problems start to bother/drain you, then you have to question how valid your friendship with her is. Take control of that friendship and allow as much or as little as you want to give.