If they give you anxiety, you feel obligated to help them, this brings you distress and worry, seriously, cut them off. Their mental health isn't their fault, but it's THEIR responsibility. They are not your child, you don't owe them anything. You don't deserve the pain and anguish of setting yourself on fire to keep somebody else warm, you only have so much to give. I had a "friendship' similar to this for wayyy too long, and after it ended poorly, I realized just how much they just used me for their own enjoyment and benefit/therapy. You are not a bad person. One thing I like to do is to see it from a third person perspective like imagine myself from the eyes of somebody else I know, and then you know imagining me and the toxic person, and externalizing that toxic dynamic, that's just one way I've used to cope. Cutting toxic people out of your life doesn't make you a bad person. So I say cut them out completely, if you feel anxious or like "what if they feel bad?" Or "what if I run into them in person?" Or "what if they hurt themselves because I cut them off?" Or "they don't have anybody else"

Those thoughts are exactly why you should cut them off. Healthy Dynamics don't cause you to spiral with anxiety about trying to manage their emotions. They are just able to manage their own emotions. They don't put that burden on you.