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The every detail that you have mentioned about how hard you have tried to get over the separation from your Ex wife, just shows how much you still love her and miss her in your life. What is really bothering is that it has been 5 years since your breakup , but still you harbor the thoughts of reconciliation , despite her disapproval on a number of occasions. She definitely has moved on in life, and now it is high time that you also come out of this phase which i would associate with depression as you are just doing your daily duties without interest , initiative and are unable to feel pleasure in previously pleasurable activities, plus the long duration for which you have stayed like this, go more in favour of Depression.
And please take note that , in depression you enter in a vicious circle , in which no matter how hard you try to come out of a particular thought or situation , you end up thinking or immersing more in it , to the extent of becoming hopeless and helpless.
As you have mentioned that you have tried dating , reading self help books, tying to keep job and spending time with your kids, all these account for positive signs and surely will help you in coming out of your present state.
But as of now , what you need is Professional help in the form of Psychotherapy ( Counseling in lay terms), which is offered by a clinical psychologist or a psychiatrist.
Right now , i would suggest you to consult a clinical psychologist and get started on Psychotherapy such as Cognitive therapy, Interpersonal therapy ,these are a few effective therapies which help in depression. I would first want you to go through counseling , without the use of anti depressants , which may be used if the psychotherapy proves of little use , which i feel will not happen.
Besides, meeting with the therapist, you continue to meet new people as i am sure there is someone really special waiting for you , and this time around when you go out on a date , please try not to compare your date with your ex wife and do not let the conversation shift to your feelings for ex wife, as no one would want to get involved with someone who still lives in the past and is failing to acknowledge the present. Believe me if your ex wife wanted you back in her life she would have done it long time back , but that did not happen, So, the early you learn to consider her as your past , the earlier you will fall in love all over again.
I hope my answer serves your query according to your satisfaction.