sb34, so sorry they have not been more positive but to honest, I think with a bit of wishful thinking on their part, they probably do think it is just a bit of a tiff that got out of hand and needs sorting out before you and AH dig your heels in. From where they are, it is case of a couple with a 'good, solid and very happy'relationship suddenly saying that they are splitting up - unless they know why you are serious about not getting back with him, they think the best way to support you is to get the two of you back together again.
I know you have said that you cannot tell them about the real reasons, but you have been amazing about dealing with the situation you are in and done so many things that you have said you simply could not do. Your parents are all grown up, I am sure that they can cope - of course they won't be happy to know that someone they took into their lives has been so awful to their daughter and grandchildren, but they will cope. At the moment, the real reason for the split probably hasn't occured to them but when you explain, you may find that they amuch more supportive.
All the best,
sis