One thing I've learned from a wide variety of sources, including those who practice mindfulness meditation and some social justice advocates, is acknowledging and experiencing emotion without judgement. Primarily, this is to be used as an act of self-awareness and can be an integral part of radical self-acceptance. What I do is I pause for a moment, take an inventory of all the emotions and sensations I am experiencing, consciously state to myself "I am feeling anxious, my heart is racing, this is a physical state of being, it is valid for me to feel, it will pass, it will not overcome me, I do not feel okay, it is okay to not feel okay, I will be okay*". I could do this with a variety of emotions and sensations, but I primarily use it to manage the symptoms of my anxiety. (Note: it doesn't make my anxiety go away, it simply eliminates the meta-anxiety, the anxieties I get about my anxieties.)
In learning to treat myself this way, I've gained enough skill to be able to treat others in this way too. Sometimes I don't have the energy, because self-care comes first. When I do have the energy, it allows me to experience the extreme emotions of others as a necessary part of their humanity. Or, to flip it, to avoid dehumanizing others by making their emotions out to be something they owe me.
So, sometimes when I'm reading things that are rather extreme in their anger or bitterness, assuming I do have the spare energy to deal with it at the time, I'll guide myself through my reaction to their feelings similarly. "This person's tone strikes me as bitter, this is an emotion they are experiencing, I am privileged to be able to see into their experiences, their emotions are a valid part of who they are, their actions are not their emotions nor are their emotions their actions, I can learn from their experiences." It helps me absorb the entire message, especially in those more difficult situations where I'm apt to take things personally (such as when people of color call out the BS white people do, and I recognize I'm included in the target demographic). I definitely could use way more practice at this, but it's a worthwhile skill that has enriched my existence thus far.
*Well... until I die one day. Eventually. :-P