You KNOW I speak from a position of "I get it." right?
At that same age, my boys loved and adored and greeted dad's visits with bouncy enthusiasm. He was so much FUN, he's like a big idiot KID himself and really, what comes up in two days that can't be joked away, or set aside at that age? It is skinned knees, or sibling squabbles and eating out and staying up watching movies that don't come near being uncomfortable topic wise.
But the kids age into movies that have jokes that aren't really funny and they see dad laugh. They have problems that they want the adult to handle not set aside. They know begin to recognize
Assface is a liar. A serial cheating, justifying, emotionally abusive, remorseless, liar.
and kids don't like being lied to any more than we do. They may not see the cheating, but they might. If dad dates, they will see him act secretive. Or meet a "friend" that is a secret. They will be emotionally abused when he snaps and is distracted or angry. They will know that his bribes to make them forgive him don't feel like remorse.
This is a hard thing for them to see in their father so be prepared for the abrupt shift in "great dad" to confused or angry.
He may be the male role model, but you are their MOM. Dad doesn't get a free pass for being a jerkface to MOM.
Try to use the EOW time to get solid and rested. And know you are not alone. What a blessing that us "single parents" aren't ever walking this parenting alone.