FB, I'm so sorry you found those conversations. I remember when I read some emails between my husband and ow and how it just broke my heart to pieces. He said things to her that were special sayings we used for each other. I know the sick to your stomach feeling, and it's going to take a little time to get over that.
However...this is about DB'ing and saving your marriage, so you must do everything you can to focus on the present. Leave the past where it belongs. Don't worry about the future. Take each day one at a time, and pat yourself on the back when you accomplish your goals. As suggested in DR, don't make your goals too lofty or long-range; instead, narrow them down to things that are achievable within a week or 2. Then, when you've accomplished that goal, expand on it a little more. This isn't a sprint but rather a marathon, and you are going to have to pace yourself.
I can see where your husband may feel under the microscope and like his efforts aren't worth it if you do throw the emails in his face. The best thing you can do for you and your marriage is let those go. Tell yourself your husband wasn't the man you fell in love with when he wrote those. When a spouse is in walk-away mode, it's truly like another person has inhabited their body.
I don't know if I'll be edited for this book suggestion...I apologize if I'm breaking a board rule, but the book "Choosing Forgiveness" by Nancy DeMoss has been a great tool for me in letting go of the past and achieving true forgiveness. I'm obviously still fighting with that, but its a great book to help you in learning to truly forgive.
Also, Mr. Bond and KD are giving you excellent advice. I think it's valuable to hear things from a male perspective!
Praying for you, your family and marriage. Know that you can do this! Love & hugs, lc4