necropolis
Bluelighter
But I've never used any psycheedelic when in a bad state of mind.
Your state of mind going into the experience is vitally important, as I'm sure you already know. Please be careful, and try to be as relaxed, calm and positive as you can before taking the material.
I don't personally have experience with 2C-B, but I found 2C-I to be quite good, so the 2C series in general might be useful in situations like yours. The Shulgins believed in 2C-B as an adjunct for psychotherapy when the person taking it was able to respond positively to MDMA, so that counts for a lot.
If I were going to take something for PTSD or depression myself, I'd turn to ketamine or MDMA first and then maybe try psychedelics after that. But the choice is yours, obviously - just be aware of your mind and body and exercise caution. If you do still end up doing this, I hope that you benefit from the experience as much as possible. Stay safe!