The best I can think of is to just keep telling him how much you love him, and that you're there for him.
It sounds like he still wants to be with you, but this is just a glitch in the plan. He just needs some time to figure things out.
So just wait it out and I'm sure he'll come back to you. If you have to just be 'friends' for now, so be it.
The more you're there for him, the more he'll see how much you truly love him.
Just make sure he gets a DNA test. You never know, this might all be a false alarm..
