I am sorry that you are hurting, and I am sorry that you have been going through this for so long.
BUT...
Honestly....
What changes have you made since the separation?
Are you still the same Woman that he left behind?
I was also a SAHM and yes I also put my children before my Husand's needs. I didn't know how much of an impact that would have on my Marriage. He felt neglected. He found someone to "fill in" the gap.
In my situation, my Husband was very immature and needy. He had a MLC and turned my life upside down.
We were separated for 2 1/2 years and were not intimate at all during that time, and our Marriage was still salvagable.
The idea behind DBing isn't just to save the Marriage, but also to save ourselves.
No, it isn't too late to save this Marriage, but there are never any guarantees as to how any of our stories will end.
I can tell you however, if you read the books, and work on your own issues, you will be a happier, more secure person.
There can be no testimony without a test. I am praying to go through this test and come out the other end with a new and better marriage then before.