First, welcome to YT, I'm glad you found us
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Okay, so first of all -- it sounds like you truly do care for this little guy, so that's the the most important thing...you care enough to make this better...and that's wonderful.
But -- you should never, ever, ever, hit him again - not EVER. Not even if he bites you. He's biting you bc you were violent with him and he is terrified and feels he needs to defend himself, okay? So, *you* taught him to behave in every way he's behaving right now....make sure you make that connection in your head.
So, it's you who needs to undo your behavior so that he can then trust and learn that he can undo his behavior.
It will take time. He will need time to learn that he *can* trust you again...but to me, it does sound like he can/will get there since he's still willing to even come by you.
Just remember though - You.Can.Never.Hit.Him.Again.