I'm so annoyed!!

So, we've been having a tough time with Jackson Lately, well, both of
them really but Jackson has been particularly disagreeable. This
doesn't have a lot to do with my story except to say that I'm not one
of those mothers that thinks their child can do no wrong.
We go to the mall play area a lot. It's new, clean, fun, comfy for
parents. Most of the time I can't get them to leave. It's usually
really crowded and the kids always find someone else to play with/run
around with whether it's a crawling baby or a 6 year old. Jackson
admittedly likes to play rough. It doesn't matter how old they are
nor their gender. I ALWAYS make sure the other child is ok with it
and the parents. We've never had an issue.
Today was a weird day though. There was a 5 year old girl that
Jackson was following around (it hadn't gotten physical yet) and she
wanted nothing to do with him. She kept crying and running away from
him which only made him chase her more. I kept trying to get him to
stop (this is where his behavior issues come into play) but he would
just go limp and scream "NO!" whenever I tried to pull him away. He
kept going back to her. I don't know what it was about her. I was
conversing with her grandmother and she was cool with it all, just
said that the girl was really shy. While we were talking I see him
chasing her again and this time he grabbed her by the waist and
tackled her to the ground. I ran over and got him off of her but he
was like a wild animal just not paying attention to me.
Probably 15 minutes later a man comes up to me from outside the play
area (it's a half wall around the whole area so anyone from in the
mall can come right up to you). I turned to look and it was a man
who had just been there with his daughters (different girls than the
one I just talked about). I smiled and said hello, waiting to hear
what he was going to say. I never dreamed it was going to be
anything negative so it took me forever for his words to sink in. He
said "I don't appreciate being called on the phone and being told
that your son was strangling my daughter." My jaw hit the floor. My
mother was with me and we were just stunned. Apparently he was there
with his daughters and his mother. Since his mother was there with
the girls he must have gone shopping or something. So while he was
gone his mother saw Jackson strangling her granddaughter and called
the father on his cell phone. Then he said "you should pay more
attention". I didn't know whether to cry or jump over the wall and
strangle HIM. I'm not saying that Jackson didn't try to play
physically with one of the girls, he probably did but it was out of
my view and I'm certain he wasn't strangling her. Obviously I missed
something but it's physically impossible to look at your child every
second you're there especially when you have TWO! And why was this
the first I was hearing of it? If a kid was strangling one of mine
and the parent wasn't paying attention I would have said something
right then and there! He was speaking to me as if I condone
strangling. Obviously if I had seen it happen I would have freaked
out on Jackson. I never even saw him interact with those girls the
whole time they were there. I'm sure he's at home telling everyone
he knows how some boy tried to strangle his daughter. Great.
I've seen this family there before too so hopefully we don't run into
them again.