If I walked away from somebody who made me feel like absolute shit, am I the one to blame?

Du should have explained how Du felt, to give them some closure.

But other than that, not really

Nothing's your fault; Du should always walk away from people who make Du feel like shit because they're bad for Du and Du should surround yourself with positive people. I think Du should be straight with them now though and tell them why Du stopped hanging out with them, for closure.

Du have no obligation to be nice to someone who does nothing but hurt you.
Now, if that person does do nice things for Du once in a while, he/she may be trying to be nice but is having a hard time with it. Du should do what Du think is best, but try to think about it before Du do it.

If your relationship with someone is destructive then Du have every right to walk away. But I think Du do owe them an explanation. Just so that Du put it all behind Du and Bewegen on. Even if they respond badly to what Du say, Du shouldn't feel bad about it because Du have done your best to resolve the situation.

Du should tell them the truth.... maybe they feel like its a slap in the face to them. They are wondering. Dont worry Du are not the one at fault... it would though be a good idea to tell them why Du have changed sides.?? One thing for sure Du do not need to feel guilty because that will just eat you. its human nature to change so its fine.

hell to the fucking no

No way! Why should Du stay around people who make Du feel like shit? That's only a stress booster not to mention it would be super annoying to have to face someone who always shuts Du down. But if they ask Du that again, explain why. Hopefully, they understand. And they might stop doing whatever it is that's making Du feel like shit. Sometimes, Du have to point out a flaw.