M.,
At first i was ready to say you were being silly, because really what is and EMOTIONAL AFFAIR, but a friendship.
BUT seeing as how you are separated, and its been 18 months,and then he went out of town with her,is still carrying on the friendship, and doesn't want counseling.
THIS SEEMS like MORE than simply emotional.
I think that if HE want to work it out ground rules need to be set,
1. ALL contact with this woman need to END
2.He needs to look for a new job away from her, as this is too much temptation, and he betrayed your trust already
now he needs to step up and show you.
3.You need to decide if you WANT HIM, We already know you can do it alone, but it seems you don't want to and you miss him,
and love him, So DECIDE if he is the one you want,
Then work at it, and let him move back in.
Bottom line as long as this other woman is in the picture he is still cheating.
Leaving this job is for the betterment of your family,
PS shortly after obtaining the new job, his cellphone should be LOST forever, when a new one is replaced, it can accidentally get dropped into water by his child.( water damage is not covered by insurance.)
I say this because it will limit his contact with this woman,
for atleast a week,
sending her a message,
ITS costly but helpful, And if at all possible speak to her face to face and TELL her don't ask her to BACK OFF. Ask her to help him respect the boundaries.
Don't let her steal your husband, he is a good man that made a mistake, Your married, he is the father of your children,he deserves a second chance.
Remember that even tho this is WORSE, BETTER is coming.