Ah - double betrayal sucks. Knowing the other couple sucks, and hearing about them in any way, sucks. I am very eloquent today, ha!
Look, the AP sounds like a drama llama, and there is really no way to reflect on her and wherever she is in this journey and feel positive about it. If she is morose and alone, that could be concerning. If she is joyous and reconciling, that would be irritating at this point as well, unless you are Mother Teresa. Nothing good can come from thinking about her very much at all.
We go through this as well -- hear little tidbits about the other couple that makes it sound like life is just hunky dory and back to normal. (They are co-hosting an event with some friends of ours and it is all over facebook, etc. None of these other friends and guests know.) Certainly this can't be the case, but for some reason it rankles both of us -- likely because we are working hard, and there is a lot of pain. Good stuff, but pain as well.
As far as the vow renewal, we have our 20th anniversary a year from this October. So, that will be almost 2.5 years out for us. I think that might be good timing for us -- and at this point I feel very positive about us in general. It is the day to day stuff that is getting me right now. I have heard of people doing vow renewals much earlier than that after infidelity, though.
Anyway, keep the faith - and karmahappens is right -- keep on walkin'.