My friend vents to me and I want to help but I don’t know how, and it triggers me (light TW, not explicit)

As the title says, my close friend has been struggling lately, and I want to help them. I offered them to vent if it would help and so they did, they were really open and that’s obviously fine but it was about things that are extremely triggering for me and so now I don’t know what to do. I don’t know what to say or how to respond because just reading about what they said they did makes me nauseous and I kinda disassociate when I read it.

This friend has been going through struggles off and on for the past year, I’ve helped them previously but I don’t want to basically say the same things so much that it doesn’t hold weight anymore. To me it holds weight, but I worry it won’t to them. I’m autistic and I don’t always know how to word things, they know I struggle to write stuff like this so they never expect anything major. I hate it though. I don’t have anyone else to talk to about how to respond so I’m seeking advice here, silly I know to some..

At the same time it’s happening at a point where I myself am struggling physically and mentally, it probably wasn’t fair to them for me to offer them venting when I knew it wasn’t a good moment for me, I just don’t know what to do now, and that’s on me.