This is sorta weird. I've been reading this book where you take uncomfortable feelings you experience in the now and you try to trace them back to some situation or experience you had in childhood.
In my case... extreme anxiety-filled procrastination/avoidance. Anyway, I've been reading this book this evening and trying to get all accepting of myself and understand why I do the things I do.
I take a break and jump on the boards and read your sitch.
I was suddenly filled with memories of my own graduation. I didn't give my dad a ticket. He had left my mom when I was 14, but we hadn't mended fences by the time I graduated and I had 3-4 really difficult years after he left... my mom remarried an abusive stepdad, had to switch schools, left our home, my dad remarried the "secretary" shortly after the divorce was final, etc... I didn't feel comfortable giving my dad a ticket. I was hassled a lot about this decision. I look back now and I completely get why I didn't want him there. His actions created a bunch of chaos in my life. I caved to the pressure and gave him a ticket in the end.
Anyway. My point. I'm 46 and still haunted by some of these events. I'm very hard on myself. I wish to he!! someone had said, "I get it. I get why you feel the way you do and it's OK. Don't beat yourself up for not feeling a certain way. You just feel how you feel and it's all good."
That episode in the parking lot had to leave a serious imprint on your son. It's bad enough he had his high school career jostled by his dad's insanity, but to have graduation tainted like that too?? What a d-bag.
I know you are an amazing mom and will handle the situation with all your mighty-ness. Just thought my hindsight, from sorta being in the position myself once, might help.
"You know, it's times like these when I realize what a superhero I am." Tony Stark/Iron Man
“Focus on what you can do, then do it with all your heart.” Lois Wilson