You don't need to say anything to sil about who is leaving who it will be glaringly obvious to all in time.

If your h doesn't snap out of it an continues with his Mlc he will take vacations without his kids, date a younger woman, dress differently. My h family was confused at first, cause my h told them it was mutual but it became so obvious and I didn't say a word


----
M 39
H 35
D5,D4
M 4
T 9
ILYBNILWY 5/18/11
Left 7/11/11
Divorced 12/1/13