How to get rid of people that I am good for but they're not good for me?

So in case, the title doesn't make sense, basically what I am asking is, how do I get rid of people that have no benefit in my life but I benefit theirs and not feel bad about it? Like there is this person I talk to, and I have wanted to stop talking so many times, but I feel bad because she has like no friends to talk to outside her job. But she causes so many problems with my life and my mental state.

How to get rid of people that I am good for but they're not good for me?
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