At some point in our lives most of us encounter someone who would be considered a toxic person, although the terminology is new enough that I know of several people who will never have heard it. With the internet available to help us diagnose everyone we know, it seems now that half the people I know on Facebook are dealing with someone who might be a sociopath or a narcissist. There are a few people from my own life who might fit those descriptions too and I know how difficult and painful encounters with them can be, particularly if these people are family members or close to you in some way. Toxic co-workers seem to be a bit of a problem as well. After fifty years of living I find myself still somewhat surprised that there are people who just seem to be okay with not being very nice, with manipulative and lying behaviour, and who are quite willing to malign you to others for their own gain.
Sometimes what is most painful is not the loss of what you thought was a good relationship with this individual but when they convince others to believe in their lies about you and you lose those relationships too or they are significantly weakened.
You have to ask yourself what kind of relationship existed in the first place if people are so willing to drop you, ignore you or believe lies about you, but the asking tends not to relieve the pain. Only time does.
I've struggled most of my life with the belief that I can make people see truth or reason if I just explain things well enough. Learning that I cannot has been a long, difficult though useful lesson. I still have to resist the urge. None of us can control what others think about us or even what they say about us. We can only be concerned with our own integrity, make our choices, learn from our mistakes, and keep putting one foot in front of the other.