My heart goes out to you. Without going into to much detail, I can tell you that I understand exactly how you feel and that my situation is slowly improving for both my husband and I (baby steps).

I am amazed that you have been able to handle your situation with understanding in terms of hearing your husband out when he talks to you about the OW.

Here is what has worked for me thus far.
1.I purchased the Divorce Remedy book and implemented the techniques outlined in the book (get this book asap). Read this book over several times.
2.I have kept a journal recording all my triumphs and failures as it relates to improving and winning back my husband. The journal has helped me measure how far I have come in terms of success and it has also served as an outlet.
3.I purchased The Power of The Praying Wife by Stormie Omartian (this has helped me tremendously). This author also has a book of prayer as it relates to your children. I suggest your buy that book also. Pray to God with all your heart and you will start to see changes in your husband. I have been amazed by the power of God and some of the things that God has done to transform me and my husband.
4.Start acting confident and looking good (go to the gym). This was extremely hard for me in the begging because all I wanted to do was lie down in bed and cry, but the more I forced myself to workout, I got more motivated to keep on going.

I don’t know if all the work I am doing will be enough to save my marriage in the end, but I can tell you that at the very least I can walk away knowing that I did all I could to save my marriage and that I will not have any regrets down the road. I am confident I will survive no matter what because God is on my side. I have learned that God comes first and your husband second. I rely on God now and not my husband and that strength radiates through to my spouse.

Hang in there! You will be ok.

Fear not, for I am with you;
Be not dismayed, for I am your God;
I will strengthen you, I will help you,
I will uphold you with my righteous right hand.
(Isaiah 41:10)