Is it okay to cut my losses and move on in this case?

I have a really rude friend, who takes me for granted and speaks to me however she wants. I’ve been insulted by her twice within a few months. Although it’s true that she’s a full time carer to her mum, I’m getting sick of making excuses for her bad behaviour, when she’s more respectful to everyone else. I’m thinking since the second time she’s been really nasty, out of the blue, I won’t go out of my way to help her make friends, anymore. I’m wondering, if she makes a habit of being bitchy, if it’s okay to just let the friendship fade and just disappear from her life? I don’t want to be a bad friend, but I get sick of being put down, when I’m the only friend she’s got left.

Is it okay to cut my losses and move on in this case?
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