You would love for exH to reach out to S19, but you want it to be organic. Then you ask for suggestions? That’s not so organic. When and if he feels comfortable doing so, he will. Without you telling him it’s OK. He is a big boy. He doesn’t need your Ok to do it if he wants to.
And maybe your son is growing into a man deciding that he wants to try new things. Why are you desperate to give that credit to your STBXH? Give it to your son for being a man and going outside of his comfort zone!
You say you are suffering for not being seen. I understand that must be difficult for you, because I truly think you believe things would be different if he could “see you now”. But he doesn’t want to “see you” or he does “see you” but right now it doesn’t change anything for him.
And it’s a really tough pill to swallow and I’m sorry. But the only thing you can do now is keep the focus off of him and proving things to him, and just live life the way you feel is right and the only person who really needs to see you, is you.