Interacting with an abused child?

I may be worrying needlessly, because in this particular case the abusive situation ended five years ago (the boy is now ten) and he's pretty normal anyway. He's my cousin. Other than being kind of poor and having an absent father, he gets along well and acts like any other kid his age. Anyway, so I only see Ryan a couple of times a year since he lives in Chicago and I recently saw him over xmas eve. Okay, I think I have to back this up. So, basically, Ryan's parents were never married but he lived with both of them until he was five. His dad beat him and his mom. Ryan's mom left his dad after he broke a few of Ryan's ribs and it was just a bad situation. Ryan NEVER talks about his dad and has never seen him since. He now uses his mom's maiden name instead of his dad's name...anyway, so Ryan is a shy kid. He's very cute (he's half Irish and half Italian) and just a sweet little boy in general. But I may have upset him. On xmas eve I discovered that Ryan is extremely ticklish. So I attacked his stomach, ribs, sides, and even tickled his neck and under his chin. And, of course, the bottoms of his feet as well which are his absolute most ticklish spot. It's kind of strange that i'm the first person to ever tickle his feet (or so he told me, and he doesn't lie)...maybe that's why they're so sensitive because he's not used to having them touched ever. Not that it matters. So, anyway, I got a little merciless and tickled him many times throughout the night to torture him. I held him down and tickled him until he cried (no adults were around at the time, we were in a separate area so nobody stopped me). I didn't mean to make him cry and I feel really bad about it now. I don't know if that has anything to do with my physical play bringing back memories of his abusive father. if so, what can I do to fix the situation? I don't think he's angry with me...but should I apologize or how do i handle this?