Return to the "Twilight Zone"

I used to be on the forum regularly. Much less so now that I'm divorced (at the end of May, I'll be marking 7 years since the marriage ended). Things involving my ex-husband impelled me to return here, and the mention in a few posts of being in the Twilight Zone motivated me to post again.

My ex has ADHD. He abandoned me and our children, first emotionally, then financially, then physically. I know that "abandoned" is a strong word, but I think that other folks with experience in the TZ can handle it. 

The stress in my life has gone down a lot now that I'm divorced. But occasionally I have reason to try to interact or communicate with my ex because of stuff involving our adult children. Here's the current TZ that people without experience with living with a person with ADHD just don't seem to understand: One of our children will be getting a Ph.D. next month, from a university out of state. She gave us a "save the date" three months ago. I bought my plane tickets. I reserved a hotel room. Her sister bought plane tickets.

Her dad (my ex) ghosted us. "Why is ex (Dad) not responding to polite messages asking whether he has bought plane tickets?" Possible reasons, possible reactions: "He's dead." "He's sick." "He didn't pay his cellphone bill and he has no service." "He didn't pay his internet bill and he has no service." "He's depressed." "He forgot." "Why do you care? You're not married anymore." "It's TOO HARD to be an adult and buy plane tickets." "He can't afford it." And so on. 

So, yes, I'm less stressed about my relationship with my ex now that I'm divorced, but also, I remain sad that I tied myself to a person who took and took and gave little to the relationship in return.