It's funny 'cause I was thinking there would be three other people who knew about him - Kingsley, Aberforth, and (bear with me here) Petunia Dursley.
I think he might have turned to Petunia to figure out how to live as a Muggle again. She might have even helped him in exchange for helping her stay out of anything wizarding.
Aberforth knew how meddling his brother was, and probably knew what Dumbledore did to Snape (I see it as nothing less than emotional blackmail and extortion). Sure, he was protecting the guy, but also putting him in an extremely dangerous and difficult situation.
And Kingsley who seems to have more inside knowledge than anyone else, and was one of the few who could fool Harry into believing he was something he was not.