awh sounds like maybe you're the only person he's getting that kind of love from. you did say he's talked about emotional and mental abuse from his parents. i don't think it would be best for you to not be in his life, perhaps he's feeling abandoned already?
you talked of his parents not wanting him to be around you. because you're gay? if that's the case then i'm sure even if you tell him it's okay he's probably terrified of it being true because his parents will treat him like they treat you.
maybe just remind him that you'll always be there for him and that you won't leave and talk to him about your relationship (or lack of) with his parents. air things out a bit.