Hello reverse, and welcome to our little corner of recovery
You sound like you have a very good understanding of how alcoholic families twist the truth and guilt people into being enablers. Your letter is firm and to the point, but still respectful. My impression is that you have started a brand new stage in your life, one that is going to be free from these toxic people.
I had to break away from my own "toxic family", and I also did it geographically. It was crazy-making at first, but it got easier with time. Those feelings you mention are exactly what I went thru.
There's a great deal of literature to help us ACoA's survive and overcome this chaos. There's entire shelves at your local bookstore and table full's at al-anon meetings. You may want to browse thru some of those.
Congratulations on a supportive husband, on 3 little ones (Suhaila is such a beautiful name) and on starting your new life
Welcome again.
Mike