How to end a long term friendship

I went through that with a guy who was like a brother for about 25 years. He went down the wrong road. Lost most all of his friends. Tried to wake him up but it wasn't happening. It came down to giving him a call and having to let him know I didn't want to be around him. Let him know if he got his act together we'd talk. You try and be patient but when it starts really getting to you have to look out for yourself. In this case, about six months later he died from an accidental (we think) overdose.
The whole thing sucked but people make personal choices.
But another option is to just keeping making yourself more and more scarce. If someone is "toxic" it's probably not the first time it's happened to them and they'll move on. Good luck.

You could go "I'm breaking up with you as a friend because your toxic." Then leave and don't indulge any questions. Just block every social media and limit all interactions.

It's the most eloquent but will result in quite a lot of emotional turmoil.

If the person breaking up were a stronger person and clear with their decisions, they would lay out offenses made towards them then state it. If the answer isn't good enough "That reason is not good enough." They might ask "What is good enough?" but that's just copping out their responsibility on the breaker upper. "That's not my responsibility. Moving on." all while keeping a calm dead-set demeanor.

I would just stop talking to them.

Say it legally. Make out an Affidavit or lodge a police complaint and seek a restraining order. It's no longer friendship but bullying & gas lighting. Make the police call the person and issue a warning, which becomes official. Some just don't get the seriousness of the matter.

Say you’ve valued your friendship over the years, but how they’re being is toxic; and that you can’t have that in your life. Maybe they’ll change or maybe it’s over forever, but they should know.

Just drift off into the sunset.

No great need to finalise anything, it has come to an unfortunate end.

Slowly distancing yourself. Eventually, sort of fading away … as in “ drifted apart”..thing

When in this situation, I have almost always sent a polite but honest handwritten letter to the person concerned. Some say that's a cowardly approach and it often elicits and angry response, but I'm not obliged to be friends with anyone if they are making me feel uncomfortable or unhappy.

Id do what @Spoiledbrat said- just avoid takking to them when possible.

When people are/become toxic, there is no reasoning or rationalizing - itll prolly just create more friction, anger or resentment.

Just try to fade out of their life

[media=https://youtu.be/kWD5gdpt4Dw]

space. we need to give each other space. space is infinite and can last a loooooooooong time.

Say goodbye and leave it at that

Write them a letter