Still in limbo...

Have you ever read Scott Wetzler's book Living with the Passive Aggressive Man? You may find some relief and answers there.
I read another part of your story earlier today and my heart goes out to. I know that pain of loving someone and sharing 'signs' and having them say one thing and do another. You deserve to be loved completely.
The way out of the pain is to let go. Easier said than done.

DG - I gotta put it to you point blank now, because we been down this same road too many times. 

Here's the choice you gotta make.  Do you want to wait around for him to see if the grass is greener elsewhere's and if he doesn't then come back to you?  Or if whoever's he's dealing with kick him to the curb and let him come back?

If you do, then you no longer need to stress.  Just let him go out and see if he can get someone he thinks is better, and if he does then I guess he'll make the decision for you.  Then you won't have a choice.

He doesn't see you, doesn't call you, doesn't show up for appointments.   He gives you a little bite to keep you hanging on.  No no.  He's not confused, trust me.  He knows exactly what he's doing.

I agree with V.  As difficult as this seems you need to quit contacting him.  I've actually gone a week and I feel much better.  If he really wants to work on it then he will call/email/text after he hasn't heard from you in awhile and wonder what is going on.  It does take 2.  I tried for a long time but I was doing it alone.  He may be as confused as you but he is taking advantage of you.  Don't let him.  Concentrate on yourself.  These things have a way of working themselves out.  You just have to be prepared for either scenario.  Good luck.

Stop emailing him. Get yourself in therapy.  It takes 2, not 1. I am sorry to say it. I was just like you. I tapped danced around him and gave him the counselors business card hoping he would go but at the end it was his decision.  You can't make him grow up or want to work at a marriage.