@Steve1:
I am so sorry for what you are going through. Here I am complaining about men when you are clearly a man suffering from what a woman did to you. I honestly don’t know how to explain woman either. They are confusing creatures as well.
All in all, heartache is heartache and I feel your pain. I felt helpless too when my relationship ended too (even though I wasn’t married) but I know its more difficult for someone to move on who has children with their partners.
Like you mentioned, you feel like you are failing your sons. Live for them. Learn to love yourself for them. Once you find that love and serenity within yourself, I am sure you will be able to find the right woman and start a whole new life with her. You deserved to be loved despite what happened to you in the past. Right now you need to focus on yourself and your sons. They need their father while they are growing up. They need him to be strong for them, be there for them and teach them things, particularly about life. Father and sons have a very special bond and I am sure you have the same bond with them. Life is too short and I know its been 4 years since your marriage ended, it might be because you haven’t forgiven your ex-wife. I think its time to forgive her for yourself and for the sake of your sons. Once you have done that, there is this powerful sense of relief that radiates throughout your whole body that I cannot explain. I felt that way when I forgave my partner for ending things with me.
Try meditation if you will. It really helps. But the most important thing is to forgive her and let go of your past. I hope this made some sense for you.