Ever had a condescending friend? I do. Any advice?

Thanks for clicking the title. I've been friends with this girl in my cl for a long time. But lately, she's starting to turn sour. She has a very negative vibe about her. Just yesterday, we were IMing and she implied that she doesn't respect me. I don't know if she was joking or not, but I couldn't help but feel she meant it. I've been having this feeling for a while now and I feel that every time I'm talking to her, she belittles me. At the moment, i feel like she is a negative person and I can't stand to be around her anymore. My question is this, how do I end the friendship without too much hle. I just want to stop talking to her completely, without being mean. Any advice?