Brianne, I love this question! The thing that helped me most in this situation is when my manager came to me and created a safe space to talk about mental health. We talked about what triggers me, what kinds of things help, and (since we're remote) we decided to have certain conversations on a call rather than on Slack. If you can tell someone is getting triggered, offering to circle back later is very helpful as it gives a chance for them to reset and get into a clear headspace. Another thing that really makes me feel understood and cared for is when my boss checks in later on to make sure I'm feeling alright and I haven't misinterpreted anything to be worse than it actually is.
I think as long as we hold that space open to talk about mental health and practice empathy, we can still have those tough conversations.