I was reading on PTSD when it hit me that there is a concept where grief recovery, twelve-step programs and a number of other things converge. That concept is honesty.
The best place to begin with honesty is when you are wrong, promptly admit it. When you have failed to get something done, do not hide, instead acknowledge it. I try to train staff who work for me to do this (it is extremely rare for any mistake they could make to do more than be an inconvenience -- if they tell me so I can fix it). When someone else fails, look for solutions, don't waste time on blaming or anger.
Part of this is letting others express their anger without cutting them off or making excuses. You can explain later, much later, and always in the context of "I mess up by ... and this is how I will avoid it in the future." If the excuse is really good, you won't need to make it (e.g. I missed a hearing because I was rear ended and my care caught on fire. When my office called the Court ten minutes before the hearing was to start and said "Mr. Marsh will be delayed, his car is on fire" no one neeced an explanation or excuse later.).
Avoid legalisms or strained constructions. "Sure I practiced piano today [in my mined, while I was asleep]" is not honest, truthful, persuasive or useful. Looking for someone to blame is even worse than not useful.
As a place to start recovery, honesty is essential. You will have real trouble finding truth if you are not honest. The truth is that recovery can come. The honest truth is that it takes honesty for recovery to happen in a real sense.