I hear you! I always thought that I was pretty good at social interaction, but now I see that I only thought so because I was so very unaware of what most people were thinking. I realize now that people who I thought of as friends were never really interested in being friends with me (and they probably signaled as much it in their NT way that I don't see).
My trouble now isn't so much in socializing in general as much as even wanting to. I used to assume that I understood what was going on, now I feel like I don't get it at all, and I don't feel much like trying anymore. I feel as if there is around a 99% chance that whatever person I'm talking to doesn't really want to know me and actually despises me for being different from them. So, I feel, why bother? My previous approach was to assume good will and friendship until I saw evidence otherwise. Now I am doing the opposite. Perhaps it's not the best thing, but this way I don't have to work so hard and I suffer far less disappointment.
DAMN! You said exactly how I feel its hit me, too. All those people I thought liked me were TOLERATING me. Sending me signals I never got.
Then, I also realized I CARE ABOUT THEM way more than they cared about me. I did care!!!! I liked people!! I thought they liked me , too, like the 12 year old I really am inside.
Pathetic.
But now I can say to that 12 year old, "Hey! You are ok! Everyone is in the same boat, they just don't know it. We are all going down, and fast."