People say don't hold grudges because if you don't forgive and forget then the weight of all the problems will just harm you further. While it isn't entirely wrong to forgive them, there is absolutely no reason you have to keep yourself surrounded by toxic people.
Take it from someone who has removed herself from several toxic friendships. This was either because I stood up for myself for once and decided no more, or they walked away and I happily closed the door behind them and smiled. Not every person you become close with is going to impact your life in a positive manner. Not every friend who becomes that texting buddy and who you tag in everything on social media is going to grow with you. This person can easily bring you down and low key drag you to rock bottom with them.
They say you won't stay friends with everyone you were extremely close with in high school. When you're nearing twenty years old this seems laughable and far-fetched because you couldn't fathom life without your click; the people who have been there for you. Not every single one of those friends are going to have the best intentions for you. As you grow up, you mature. This is to say not everyone matures with you. It's when you have reached your stage in life when you can see clearly that the grass may be greener on the other side and not everyone in your life deserves to make that journey alongside you.
There is absolutely nothing wrong with cutting that cord. No one is ever going to force you to remain bonded with the same people forever, especially if that individual(s) have proven that they aren't helping you build one another up. As you grow and experience different parts of life you can soon find out who is actually there for you and those who see you as another form of a bank, a taxi, etc.
Let me tell you a story. I once roomed in college with a person I knew from my senior year of high school. She was sweet at first and helped me get my bearings around the campus, showed me around and aided me in getting used to how things were there. Things took a nasty turn for the worst when this person began flipping out for no reason at all, sending nasty texts and taking everything much too seriously. I soon became her ATM for cigarettes and food and alcohol. I soon became the punching bag she could take her anger out on verbally and it slowly ate away at me. I began walking on eggshells around her and watching every single thing I said as to not trigger another meaningless argument. There were numerous fights all stemming from her switching to furious anger within seconds due to the fact that every word that came out of my mouth or fingertips bothered her. Bystanders would coach me to end the friendship because it clearly wasn't benefitting me at all. The day I told her how I felt once and for all and hung up that phone was to this day one of the best moments of my life.
This person was hurt of course. They proceeded to send me multiple messages all fueled by anger. I had said what needed to be said and eventually those one-sided conversations halted. I don't feel bad at all for I did what had to be done for my own well-being and mental health. After a couple months I began feeling much better about myself and all those insulting words that she threw at my direction slowly became a ghost that ceased to even be a memory.
Toxic people are not worth having in your life. If a "friend" continues to chip away at your own happiness, doesn't even realize he/she is doing this, then they are someone you should leave in the past. Chance after chance only breaks the bond until the only reason the string is still there is solely out of fear of hurting the other person. You reach the point of your life when you have to begin to look out for yourself. It's not selfish, it's not cruel because sometimes you have to walk away.