What good does it do to let his parents know you are committed to the M?
I understand thanking them for everything they have done
What is the right time, no idea. I waited till I thought there was no hope for reconcilliation before I did that...and it got awkward. W's parents started wanting us to read books, etc...things I would never suggest to W, so then had to politely say that although I might be open to those ideas, that they needed to be there to help/support their daughter not me...

I think you need to evaluate your reasons for wanting to do this, and then decide for yourself when is the right time for yourself in your siutation. Starsky is right, H will NOT tell them aboout an A

M39 W41
Two children
WAW bomb dropped 11/7/09
Piecing Aug 10 - Nov 10
No longer piecing...Nov 10
Separation Jan 11
EA ends again Feb 11
Piecing attempt #2, Mar 11