What else is it that you need answered? It seemed your original expert answered your question.
No one will wait forever for someone to, as you put it, "man up." She gave you 20 years of her life, waiting for you to change. After she left, you did what you needed to do (and what she had asked you to do) to make things right....but by then it was too late. Too many times, we don't make changes when our partners ask us to, until when they finally get tired of waiting and give up and leave us, then we take them seriously and do what needed to be done. Unfortunately, by the time the 'good' happened, too much had happened to the affection between the two of you. You said she always wanted you to get help, but it seems you didn't do it when she asked you. You seem to have waited too long.
At this point, all you can do is to keep taking the medication and getting help. Some day, if the new man doesn't treat her right, she may consider coming back to you if you have kept the changes going. She may need to see that you're not making those changes just to try to get her back, but that you are doing it because you realize you have to do it for yourself.