I'm so sad for you and for your sons. But it does sound as if, for the three of you at least, there'll be no grieving mixed with bitterness or anger, or mourning for a huge part of your life which you wish you hadn't wasted.
Imagine knowing someone for all that time, imagine having two wonderful sons to share and who know their father and still see him. Imagine still being good friends! It says a great deal about you as a person, soop. Then you finally know that he's found peace when his life, his health and his mind has deteriorated and he no longer has the quality of life which he deserves. You must have some lovely memories and you've a wonderful Mr Mac who can share all that and understand what this morning has brought to you.
Hoping so much the you can take some comfort from the relief that he's no longer struggling. Your lovely sons are there and a wonderful legacy, as you say.
Sending all good wishes and a massive hug to you, and every sympathy to his widow and his children on such a very sad day.