There are many articles and information on what to look for in unhealthy and toxic relationships. When people talk about this, they're generally talking about romantic relationships. Unfortunately, friendships can be toxic too.
Friendships should be supportive and uplifting, not something that brings you down. It is hard to realize when a friendship is unhealthy or becoming unhealthy because our friends are huge parts of our lives and usually end up being more like family than friends. We invest so much time into these relationships, and we want to give them the benefit of the doubt, but we also need to put ourselves first and realize when a friendship is not healthy for us anymore.
If you are constantly putting in way more effort than someone else, or they only make time for you when it is convenient for them -- that is not a healthy friendship. Sure, life gets busy and sometimes we can't give as much time to our friends as we used to, but friends should still make time for each other. Whether it is a text here and there to check up on each other or a quick coffee date. Life is busy and that is OK, but there is still ways to make time for someone you care about.
Friendships where your friend constantly puts you down or makes fun of you is not healthy. Sure, sometimes friends joke around about certain things with each other, but when it gets to the point that it is hurting self-esteem and your friends just seem not to care... is not okay. Friends should be uplifting and help you feel good about yourself, not worse.
If you constantly feel like you are getting left out, maybe your friends aren't the type of friends you want to have. We all know how hurtful it is to see pictures of your friends doing something that you weren't invited to. Friends should want to include each other, not leave each other out knowing someone is going to get hurt.
To me, it is harder to "break-up" with a friend than it is a boyfriend. Friendships don't usually end as abruptly as a relationship, and it is hard to tell someone you can't be friends with them anymore. It usually happens slowly and with each other's feelings get hurt. It is hard to end a friendship, especially when you know you're probably going to lose other friends in the process, but you have to do what is best for you -- even if that means the possibility of losing other friends.
It is hard, it hurts and it is painful. If someone is toxic to you, don't continue to let them be in your life and hurt you even more. Let go of the people that keep bringing you down. Life is too short to be friends with people that constantly weigh you down.
I've had my fair share of friendships that became unhealthy, and yes, it still hurts. I still get sad sometimes, but some people come into our lives for only a season and to teach us a lesson. Not every person is meant to be in our life for forever -- and that is OK.