Boyfriend of 12 years never sees or calls me

You are right. It's probably an illusion. But it was nice as I never experienced even that level of closeness to someone. And I am not sure if this broke me, or I was already broken before, but I feel like I don't want to be around someone all the time or even every day. Except for my child of course, as that is different. I feel like I don't want anymore someone in my bed every day, or to see some man every day. IS that normal? But I do want to have a weekend or a whole day with someone, I want a sleepover sometimes, I want a time to travel together, to take a day off together, and casual meetings, not "I have free 3 hours in two days, lets meet then!" but instead "can I take you to coffee?" or just not to be that exhausting.
And you are right, Divine and Azul, we probably can't be just friends. I might be stupid for this, but I still have feelings for him, but also, I am tired of being in such exhausting relationship. I am not a mashine. I can't just function by schedule. When he has spare few hours in week, lets meet! I am too old for that. And it's humilliating.
I do feel sorry for him. He might look like a villain in the way I described him, but he has so many issues. Sometimes, when he states his reasons, I can't even grasp how horrible his problems are and what the hell did his parents did to him to make him that way. He is so intelligent, funny, sweet, yet he is so terribly dependent on them, and he sticks so badly to his tight "schedule" he invented by himself (to please them probably)! I sometimes listen to him and I don't understand anything! I see this sweet smart man saying things that have no sense at all for me. To be honest, I believe his parents had the best intentions, but wanting so badly to protect him, they went terribly wrong path in parenting by overprotecting. but that's just my theory.
he wants me but on his own terms, and his terms are something I can't handle. It's too hard. And if I can't he just quits the relationship, so easy, just gives up. It's easier than to change at age of 50. Oh, he wants to be friends but is it even possible? I feel like invested my best years in totally wrong person. Luckily, at least I got a child custody, so I am happy about that.

You only know what he tells you. He possibly doesn’t want you to meet his parents so you don’t find out what’s really going on. I call BS

In my opinion you shouldn’t be so hard on yourself for giving you time to try to understand him. It’s clear you are a caring person, you were living a very hard situation after what happened to you in the previous relation, then it’s the thing about you also needed a lot of time for your kid and yourself.
I don’t think you are less intelligent than any other person and was your fault. You were vulnerable and you saw affection. We don’t know the whole circumstances in this guy’s life, of course, there are red flags but nothing proven.
There are many types of relationships. Who we are to judge others’ people bounds or relations.
What it’s important is that you don’t want to go on this kind of relation and you have all your right to choose.
Don’t let him or anyone else make you doubt about your choice. It’s your life and you need something else now.