hi Kat
you may not know, but there is a forum here at psych Central under self injury which you might find helpful. Perhaps contacting your therapist to say that you are in urgent need of help would bring you a quick response?
There is Nami the organization for the mentally ill and googling them will put you in contact and in many areas they do run peer to peer support groups to give you people to talk to. Inquiring whether there are any depression support groups in your area, might throw up something. The public library me know and your doctor also. You are right loved ones don't realize what depression is like not having ever experienced it. Although things can be downloaded from the Internet on how to support someone with depression. I hope and pray everything will get better for you. Take care. Have a really great day. God bless and best wishes from your friend Francis