Adding to the "is this people online?" crowd.
I lean leftwards because I want more people to get the help, dignity and peace they need and deserve. Now I feel a wave of being told to "harden my heart" and I feel scared and isolated.
Harden your heart against whom? Who is telling you this?
I don't have it in me to become a martyr and estrange myself from most people any further,
I'm taking "martyr" here in a figurative sense, but no you don't have to isolate yourself from people to be effective. I would argue it's counter productive, unless you are working on something that requires secrecy.
I get nervous with the leftism I see so often expressed as wanting the bad people suffer,
I don't think wanting people to suffer is "leftism". It can certainly be people on the left expressing anger and hurt.
and that anything short of revolution is not just not good enough, but worse than doing nothing.
I think this is short signted. What is revolution anyways? One violent clash and the world is fixed? No, it's going to take a lot of different people doing a lot of different things. Isn't mutual aid a revolutionary act?
And then I have constant guilt that I'm judging people more discriminated than me for how they express things; that my fears aren't valid and expressions of privilege.
Is this online? It's not about you. Let people be angry. They have reason to be angry. If you take it personally, maybe ask (yourself) why? Are you harbouring guilt for participating in something harmful? Can you stop doing it? Can you turn this into something positive, maybe amplify the voices of the less privileged without adding in your own voice, so that others can hear and learn?
If it's not online my response is mostly the same unless it's someone you have a relationship speaking to you directly. In that case, maybe try and understand why they are telling you these things. Are they asking you to change? Are you a trusted person they are venting to? Etc.
By now I'm feeling emotional burnout, I get annoyed by any respone that isn't in-depth analysis because it just feels like watching the same responses happening over and over and never going anywhere.
It's okay to take a break, comrade.