So sorry for all this strife you've had to go through while pregnant, that's just an awful story! I totally agree with AnotherStander -- so many people on this board have had waywards temporarily return and are quick to declare "piecing" when in fact its just a temporary stay of execution for the relationship.
The problem with pursuit is that you put yourself in a position to be devalued. You're telling the person that they can have you back at any time and for no effort. People don't value things that are freely given, they like things they have to work for and earn. When H can return to you with little to no effort, he won't value you from the moment he returns, its just a situation of convenience for him.
Your H definitely needs to understand that you have moved on from him and that he *cannot* come back until he earns his way back. Until that happens, you'll see the same pattern where he might temperature check you from time to time, or return with no commitment when it suits him and then bounce out again. There's no consequence for that behavior, he has nothing to lose by doing so because he knows you will continue to take him back.
In short, he won't come back to stay and be motivated to do the work until he believes he can't come back. He won't believe he can't come back until YOU believe you don't want him back. That levels the playing field for a new relationship to start where one of you isn't "one down" to begin with.
In addition, you need to be good with yourself without him -- you need to be happy and confident. You need to be the best "you" you can be, you need to lead a life that anyone would want to share. If you can do that, then he'll be lucky to have you because you are the prize to be won.
The challenge, therefore, has really nothing to do with him or what he thinks, feels or does, and everything to do with what do YOU need to do to be happy, excited about life, and the best person you can be?
Focus on that.
Acc
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