Girlfriend, I left my AH after 20 years last summer. I know the sadness of which you speak. But let me assure you (though I'm a young thing in comparison -- I'm only 45!
) that there is a life on the other side of leaving. A life that can be good.
Divorcing an A is radical weightloss surgery -- except the weight doesn't come off your rear end, it comes off your shoulders. I'm sorry you have to go through it, it's not easy, but it's still better than the alternative when you've come to the emotional place you're at.
Big hugs to you.