Am I the bad friend or are they toxic?

So I have this friend, let’s call them B. B has very questionable habit of making “sarcastic” comments or “jokes” and just not really a nice person in general (in my opinion).
In our friend group, no one likes listening to them since they usually consist of calling us “cowards” (the most acceptable one) to abandoning one of our friends on a geography trip for being “lazy” or “dumb” and justify it by saying “I just feel like if I work with *name* we will work better since *friend’s name* doesn’t really work and she isn’t really smart on the academic side” (not saying she is saying them on purpose, I would give them the benefit of the doubt and say she is unaware), in fact we find it offensive. Now the problem is that, we have had the conversation with them about these comments, they claimed they would improve and stop making these comments; they did for a while but they eventually returned to making these comments like they did before.
So I have kind of distanced myself from them, I feel like if I keep staying close I am eventually going to get hurt again. Now I don’t do the usual conversations on the stuff we like, and I couldn’t really bring myself up to look at them in their eyes, it’s felt uncomfortable and awkward so I have been just smiling as greeting or sometimes I don’t greet them at all (I know it is really rude, it makes me feel like a bad person and I am willing to take 100% accountability)
Every time I think about this, I feel like I have been neglecting them, no matter what they did. Am I the bad person here? Or am I overthinking? And if I want to cut them off, what should I do?
I have tried to fit in as much of the information as possible, I know I am not a really good person either, as you can see. But still, please be 100% honest
Thx for listening to my rant and thx in advance!

They sound annoying. I mean, sometimes people are far too blunt. Do you think they mean any harm by these comments, or is it a lack of filter?

I don’t think they mean any harm, from what I know about them, I think they just lacked filter.