Short tempered, lack of patience, negative moods - Coping mechanisms?

Hey folks,

Got a bit of a personal problem here and looking for any advice or support.

Over the years I have had a few issues, but thankfully recognised them and sought help for them.

Just before christmas i was in a bit of a pickle and again, saw a therapist and overcame my issues. Come January i started training for a marathon, which was 4 months of 3-4 runs a week. Something i really focused upon. 

Since my marathon, i have been having the odd mood swing. This has left me without patience, short tempered and ultimately speaking to my wife and daughter (who is 9) in a very condescending and negative way. This has come to a head with my family. My wife is on her last straw with it and my daughter has said she has 'lost her dad'. Which is utterly heart breaking.

I mention the marathon training, as this is the clear line in the sand where i changed, according to my wife. And in hindsight, i tend to agree.

I am booked in with my therapist for next week and hope to resolve these issues. what is frustrating is i cant pin point what the cause or trigger is. I will see something that i dont like and it will start the process. I will start nit picking, making snide comments and generally not be loving, caring or any of the positive traits that i know i can be. It can be something small, like dishes not put in the dishwasher that starts the downward spiral. And i know this isnt the issue, but its a reason to 'get moody'.

I am trying to stay positive and see this as a challenge to overcome, rather than spiral downwards and be harsh on myself (despite knowing this is all my doing).

Has anyone else been in this situation? What did you do to overcome it? Do you have any coping mechanisms that you use to snap you out of the negative mood you are in? Did you get to the bottom of the cause?

Clearly being focused on something like a marathon kept my mind, body and soul in check, but ideally i'd rather avoid being like this, rather than rely on a training plan to keep me sane.

Any thoughts, feedback or help is much appreciated.

Thank you in advance.