Funny that. You could have stopped. You COULD have thought about what you were doing.
At every step of the way between first meeting and shagging him there were a MILLION opportunities for you to make a choice NOT to do this.
I couldn't give a shit about your MM, he's not here. He's at home playing happy families with his wife and children.
You had the looks, the chats, the thoughts. THEN you could have checked yourself.
There's the sitting next to other normal people, married people knowing that YOU are a woman contemplating shagging someone elses H. THEN you could have stopped it.
There is the meeting where it looks like the relationship is going to go further than it has done up until now. why did you go through with it? Why did you agree to meet. You could have said NO.
There are the touches, why did you allow/make them? You could have said NO.
Then the kiss... even the simple act of a kiss has millions of nano-seconds in which you can pull back. You could have said NO.
But no. Silly me, you were powerless to stop it. Clearly I must be wrong here, you must have slipped on a comedy bar of soap or a pesky banana skin and with laser guided precision, you managed to land on his dick? 
So what IS your life that it is less than mine? I can play shitty existence all day long. I have more to gain than you, and nothing to lose. Except my dignity.
I call Bollocks on this thread. I smell Eau de Bullshit.