There are 7 billion human beings on planet Earth, so if you are friends with someone who makes you feel crummy every time you're in their presence; directly (or passive-aggressively) insults you; is a racist or sexist; a liar; uses you for your work position, financial ability, rides, or any other aspect, it's time to get rid of them. As research has shown, who you surround yourself with matters — you take on at least some of that aspects of the people you spend time with, so if someone is negative and mean to you, it's not only bad for your mental health, it could lead to physical issues too. 

At the same time, as you get older it can be difficult to make new friends (though not impossible; I wrote earlier about how to make friends as a grown-up). So how do you know if it's time to say goodbye to a friend — and how do you do it? (And I feel like I have some real bona fides giving this advice; I've separated from three very good friends over the years. Remember, that just makes room for positive, good friends in your life!) 

Fights are OK, not listening isn't: A good, honest friendship between two adult human beings is bound to be fraught at times, so if you generally have a good relationship with your friend, and have occasional blowouts, realize that's perfectly normal — and it's pretty great that you and your friend can speak openly and honestly. As with any relationship, it's great to talk it out (and reconnect) after a fight, once you have cooled off. But if you routinely argue with your friend, and he or she refuses to listen or acknowledge your point of view, or the friend repeatedly brings up topics about which you always disagree simply to provoke you, or talks over you (basically talking at you but not with you), that's disrespectful. There's a difference between honest agreement and provocation.  

Lying is not OK: If your friend lies to you — whether it's about who she is, her job, her family, or other aspects of her life, get out now. There are a surprisingly high number of liars in the world, and if a friend can't be honest about who they are with you, they have bigger mental health issues than just lying. Liars need people in their life who will listen to their stories, and a friend in this instance is just someone who will listen to and believe their stories. But that's not a real friendship. Of course, I'm not talking about white lies here — how much you spent on your vacation, or whether someone's butt looks big in a pair of pants (though if your good friends can't tell you that stuff, who will?). If you find yourself in a relationship with a liar, that's reason enough to end the friendship. 

Demeaning you is never OK: It should go without saying, but if your friend is abusing you verbally — that includes insults, snide comments, and saying negative things to other friends or coworkers — end it, now. 

Using you is not acceptable: If someone is only your friend for the benefits it brings them — access to certain places or people, money, rides, or freebies (food, yoga classes), they are not your friend; they are using you.

Not acting like a friend means they're not your friend: If you are constantly doing things for your "friend" — meeting at their place or taking them out, calling or emailing flying to see them, sending them gifts on their birthday — and they don't return those things in any similar way, that isn't a real friendship either. 

Sometimes some of these things can be hard to see clearly, but if you are feeling uncomfortable about a friendship, take a close look and ask yourself if one or more of the things above are happening — after being friends for a long time, these instances might be hard to see. That was the case with me and two so-called friends that I had known since childhood and high school, respectively. Once you are honest with yourself about the fact that your friends aren't really acting like people who love and care for you, there's only one thing to do: break up with them.

How?

The only way that works is being straightforward and concise. I ended one of my friendships in person (messier than I wanted it to be, but effective) and another via email. Keep it simple. Tell the person you want out of the friendship. I wished both of my friends the best, but told them that we weren't cut out to be friends anymore. After a minimal back-and-forth in both cases (via email and in person), I cut the discussion off. And I refused any kind of contact for months (and in one case almost a year) later.

Once you've had your conversation, be strong — it's tempting to go back and explain yourself. Don't. We all have the right to end relationships that are hurtful to us for no other reason than that they are hurtful. You don't need to justify moving on.

How do you know you've made the right decision to break up with a friend? For me, immediately afterwards, I felt an overwhelming sense of happiness and freedom. The relief was overwhelming — though I did feel some guilt too, and that's normal. But when you make the right decision, you'll know it.  

Related on MNN: 

The opinions expressed by MNN Bloggers and those providing comments are theirs alone, and do not reflect the opinions of MNN.com. While we have reviewed their content to make sure it complies with our Terms and Conditions, MNN is not responsible for the accuracy of any of their information.