J.O.
How big was this 5 year old that he could drag your 7 year old son that hard?
What it sounds like is 2 kids that have yet to learn how to interact properly with one another. Does your son have any other underlying issues? At 7 he really should know that hitting is not okay. the 5 year old sounds like a 5 year old (not excusing his behavior..just saying).
Honestly I wish parents would learn to not put the children in the middle. Believe it or not many problems with children will work themselves out in time with age and maturity. Instead parents get all huffy and create ill will and bad feelings which them follow these kids through school. so not cool.
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My oldest boy who is now 21, had some aggression issues as a young guy. At the time he just had a "language, comprehension disorder". It effected every area of his life. Speech and comprehension being the largest one.
His weapon of choice wasn't hitting..it was biting. To the point that he would draw blood, mainly his little sister, but never opposed to another person when his frustration levels were high.
Now at 21 many believe including therapist (as a teen he was diagnosed bi-polar) believe that he sits on the autism spectrum. It just wasn't as known back then.
Here's the thing, no one was every the reason my son bit and on occasion hit. No amount of provoking was an acceptable excuse. The consequences were swift and immediate. Until the issue was brought under control, who he played with was severely limited.
Only parents of children I trusted were allowed played dates. Parents I knew who would have my child's best interest at heart. Parents who understood this was an issue and were willing to work with me and my son, and only kid s who were older then him and able to deal with the issues that would come up. Older kids are great in this respect, because truthfully some of the very behaviors I was dealing with in my son were 'normal' behaviors in younger kids. Just not acceptable from an older child.
I understand I really do, but you are trying to convince others that a manipulative 5 year old is the problem. He's 5 momma. That age for some kids is about learning to navigate friendships, rights and wrong, it's not about manipulation it's about learning.
Recognize that your son was a part of the problem, your reaction was part of the problem.