I'm glad you feel peace this am. And, I'm glad you're thinking along the lines of what I was offering as advice.
Remember, your H does not make all of the decisions in the marriage. You do, too. He may be unhappy, and/or have periods of unhappiness, but so do you. The difference is... You're just not stewing over it silently, then lashing out, and/or dropping bombs. You're actively trying to turn this around.
Let him feel a little bit of what he's dishing out. Let him know YOU are considering what to do, as it 'ain't' workin' as is!
If he's truly being faithful... There's a really good chance that seeing you turn the tables on him will make him appreciate what it is he is considering...
And, the 5K sounds awesome!!! Nice to have a PT to get you ready! You will not believe how much stronger you feel after running. It's amazing. Really good, clean, think time, too!
Me? Well, I have an exciting day... I work from home, so, I'm doing that... but, I'm so lucky to be getting new tires, an oil change, AND an alignment! YAY! YUCK! Merry Christmas to me!
Me-46, D-21, S15, S13
After many years w/my head in the sand... I FILED Divorced 6/2011
The average woman would rather have beauty than brains, because the average man can see better than he can think.
And, I'm glad you're thinking along the lines of what I was offering as advice. 
