It is unfortunate that he hasn't blocked her, but I think your IC is right. Your H fears needing you more than you need him, and knowing OW is out there is probably something that makes him feel more secure and in-control. If things truly are going well, then you really should forget about it -- remember that what you focus on expands. If you focus on this, you're headed for a confrontation.
If you focus on your changes and what a good partner you're being, that will expand instead and OW will not be a concern.
I know it's hard, but reassure yourself that you are worth having and if H chooses to stray again, that will be his loss. Live your life that way and you'll be in a good place.
Accuray
Married 18, Together 20, Now Divorced M: 48, W: 50, D: 18, S: 16, D: 12 Bomb Dropped (EA, D): 7/13/11 Start Reconcile: 8/15/11 Bomb Dropped (EA, D): 5/1/2014 (Divorced) In a New Relationship: 3/2015
