We should keep this in mind: not everyone in our lives is our friend. With some people, we share far more time than we should, but once we see that, we can't unsee it, and we have to act.
It hurts; it's objectively horrible, but some people will use anyone who'll listen to dump their emotions on, and they will not feel the need to reciprocate. They are out there, and we should stay away from them. Realizing someone we thought was our best friend is like this can be painful, but at the same time, it's a great opportunity to remove this energy from our lives.
We might be used to always being the one who makes plans and keeps the friendships alive, and that can be good in some relationships where the other person is a little bit less proactive but still loves us.
But there are other relationships where we should step aside and see for ourselves that the other person doesn't want us there if it's not for an unpaid therapy session.
I know this can sound controversial, but when things reach this point, I don't recommend talking. What is there to talk about when you've already discovered your friend is a user? You can't explain basic empathy or friendship to a fully grown adult.
If they didn't have time to learn that as kids, do we really think they will learn it now because we tell them to?
There are plenty of friends in the sea, or whatever. Let's invest time in those who know empathy from the get-go, and free ourselves from being a free psychologist or an unpaid kindergarten teacher!