SoAsh...you asked if it is ok to pray for your H to have his heart soften. Of course you can pray for anything you want...however, that is not how it works. Your H has free will. You cannot pray "against" someone's will. Even God cannot change your H's will, because it is free. At this time, your H is exercising his right to free will in his choice to not be open to a reconciliation.
Can you pray for him to change his mind? Sure. But God cannot change it. Your H may change it on his own. I hope you understand the difference.
I still think that you are not really seeing the full issue here. As in, if the shoe was on the other foot, would you really want your husband back? I know you will try to apply your current feelings to that question and will try to answer yes...but very likely, if the shoe really WAS on the other foot, the answer would be "no".
There still is no harm in praying for him to have a change of heart...but I think most of your prayers should be sent to heal him of the pain of what he has gone through. IOW, your prayers for him to have a change of heart are actually selfish on a certain level (please don't take that as mean). Whatever HELPS him is what you should pray for...and at this time, HE feels he should move on and that is what will help him.
Your prayers for yourself should be to learn real contrition. If you were truly in contrition, you would understand why he cannot have a change of heart at this time and you would want what is best for him. I know you think that reconciliation is what is best for him, but that is not what HE thinks.
I'm still very sad for you. Trust me that I do know how painful this is.