See You Soon

This is about insecurity. The line, "So you lost your trust and you never should have" states that the person was so insecure that there was no reason to lose trust. Then he says, "Don't break your back if you ever hear this, don't answer that," meaning not to fret - time will do it's thing if you just think and listen. The line, "In a bulletproof vest, with the windows all closed, I'll be doing my best and I'll see you soon" means that the person protects themselves, not letting anyone in. The other person will be doing their best, seeing them soon when the insecure person has gained trust.