A helpful tip to get myself writing notes instead of lashing out at friends was to send DMs in a chat I was only in. So it felt like I sent it, but without the destroying my friendships part. For each message I'd also write notes down elsewhere and when I was done I'd copy-paste it to to wherever I wanted to send it. Once I got used to it, I would just write notes on my phone and then screenshot it and not send it anywhere. I still feel vindicated at the time, but now I don't have to deal with the aftermath. It's also good at documenting what I am thinking and what lead to it.
Hopefully someone else finds this useful :)