How nice that he has had problems apologizing and is getting better at doing it! That's great.
And that he apologized for the A!!!!! That's REALLY something. My husband hasn't done that or mentioned much of anything about it. But he has showed a lot more caring and "love." Also, my husband did stop the divorce (with zero pressure from me). That's huge.
In the past I did "flip out" when my husband had to travel to where OW is (another part of the company he works for), and after creating some problems I realized I can't do that. I have to trust that he will make wise choises. I know it's an uncomfortable feeling. I think my husband may need to go there again later this month. Like with DBing I just have to focus on me and keep trying to be the best person I can be. I just can't let myself freak out or worry. That doesn't help or change anything. I've learned it can only make it worse.
But one thing that did help is asking my husband to call once a day to just let me know how he's doing (most husbands do that anyway so I don't think it's asking a lot). And rather then expressing worry about the OW, I said I just wanted to hear from him so I'd know he was okay, and hadn't gotten into a car accident or plane crash.
There is no arriving, ever. It is all a continual becoming.