S15 is old enough where he does not need constant adult supervision. Good.

Wait until Friday afternoon, then text this:

W:"H, something important came up. I will not be home this weekend. Nothing you need to worry about. S15 is planning on bla bla bla. I will let him know to contact you if he needs anything."

"What is best for my kids is best for me"
Amor Fati
Link to quotes: https://www.divorcebusting.com/forums/ubbthreads.php?ubb=showflat&Number=2879712