Sometimes, when the ball is in the other court.... I need to go off and play checkers.
Call a gal friend and go to lunch! Join a reading club (check at the library). Volunteer at the animal shelter (they need blankets, towels and bleach, btw). Call the senior services and see if they need someone to come read in the evenings.
Once you are all tangled up in these other events.... the time will go by fast, and you may discover that both your son and your ex/sorta will need to "take a number" to get a bit of your time!
(((hugs))))