Why did he make himself so isolated and completely dependent on you in the first place? "Can't use a computer?" It sounds like he had some deep issues and really does need psychological help.

Seriously, a therapist and your attorney on your side should be helping you right now.

Maybe writing him a letter saying how he needs to get help and learn to be an adult and move on would be better than calling or visiting, adding more closure. As hard as it is, no contact is also an option. It doesn't make you look bad. You tried everything and have already said everything. Now you have broken free. There really isn't anything to say to him except that you hope he gets help and becomes well and moves on.