Pack, I get what you are saying about not wanting to be fake with her. However, I think you just continue to DB. You treat her with politeness. You are kind like you would be to a total stranger. But you do not over share with her, just like the cashier at the store.
Her: "Hi, how'd it go with them?" You: "It went well. We did some fun things, I am sure they will tell you." Her: "Ok I will have to discuss it with them, but they seem like they enjoyed it." You: "Yes, they really did seem to have a good time." Her: "Okay well, we have some fun things planned to, we are going to go here and do this." You: "That sounds great! They should enjoy that. Hey, I have to get going, I have some place I need to be."
Then leave.
R2C likes to say "Never stop DBing!" I agree with him. You DB with her for the rest of your life. Not to save the marriage (since that is now beyond all of that), but to have a friendly, polite R with her but still keep her at arms length.
M(53), W(54),D(19) M-23, T-25 Bomb Drop - Dec.23, 2017 Ring and Piecing since March 2018