I don’t think it’s wise or appropriate for 21 year old to engage in this manner with16 year old. He is too young and clearly isn’t able to process what happened and getting entangled with kids could cause your problems. legal problems, and problems with their parents. As a parent I’d find it unacceptable.

Block him and seek therapy. Therapy can help you to learn how to build friendships with adults, not kids. You could also benefit from learning how to set boundaries. If you barely know someone and aren’t romantically interested regardless of their age, but especially if they minors, it’s unwise to sleep with them in bed laying your head on their chests and hold hands or otherwise have excessive physical contacts. Please seek therapy.

And I hope there are no legal consequences of all this ( if he threatened to report someone else for molesting him, and it wasn’t even true, who knows what he can say about you with all the cosleeping you did with him etc). He is unstable Good luck.