Learn to move on discreetly without broadcasting your availability to him or anyone else.
Living in a fantasy isn't healthy, especially when your parents are supporting this behavior instead of helping you move forward. Consider asking your parents to stop mentioning him. If they don't respect your request, you might need to distance yourself from them.
Accept that he's moved on and respect his decision to not reconnect with you. He doesn't want you in his life anymore. It's possible he only responded to you out of politeness, and your past attempts to contact him may have made him uncomfortable.
If you truly care about him, respect his boundaries and privacy. He hasn't reached out despite ample opportunities. Silence is his answer.
Contacting him won't give you closure; it will only trap you further in your feelings. Disengage, block him, and stop checking up on his family online. He might allegedly avoid social media because he knows you're still involved in his life, making him uneasy.
Your relationship with him wasn't as you imagined; both of you were dealing with mental health issues and were codependent. Reconnecting would be harmful for both of you.
The relationship may have only been trauma bonding.
By keeping yourself open to him, you're allowing him to use you whenever he wants. Even if he returns, it doesn't mean he shares your feelings.
Neither his rejection nor reconciliation would bring you closure, especially if you're unwilling to accept it.
Your behavior is disrespectful and shows a sense of entitlement. Leave him alone.
There are free counseling and therapy resources available if you're serious about moving on.
Living in a fantasy is wasting your life. I understand you're hurting, but you need to let go of this obsession before you do something irreversible. Many people, possibly including him, find your behavior unsettling.
It's time to face reality.