I too am a combat veteran, OIF 1&2. I too went through PTSD problems and counseling. I too spent almost 8 years in the Army.
I am not trying to downplay your situation, but in my mind I would have NEVER accepted money for an item and never shipped the item. Even if a situation came up immediately after receiving funds but before I could ship said item, I would have contacted the buyer IMMEDIATELY and gave them the option of waiting or a refund.
Anybody who doesn't think that way never had good intentions from the start.