Hi I thought I'd add my experience as I think our DS have been in the same boat.
I have a friend who is far more of a mollycoddler and passifyer than me. I'm more a shit happens deal with it type of parent!
My DS is very responsive if I say please don't........., or please do.........
My friends children are more of the ignore mum camp - usually because it works, or throw a hissy about how unfair it is because, yep......... it works!
Whenever anything happens they overdramatise it - yelling at the top of their lungs about how DS ruins everything, how they hate him, how they want him to go home etc etc. Although friend says 'don't be silly, of course you don't' there's never any consequence for name calling, hitting out etc.
So on the surface of things my DS is made to look like a bad person, he is also non confrontational so will try and quietly compromise but they will talk over him, loudly, stating THEY are trying to talk and he NEVER listens.
It seems like this is whats happening here. I'm not saying that your DS behaviour has been flawless, no 5yo's is!, but to me to say he going swimming is not a major deal. I will also say I wouldn't assume the worst re hitting with rope incident etc - my DS wouldn't bother even letting it register let alone ruining his day so he suffers the same but just doesn't seek to incriminate anyone with it iyswim?
Other children are very good at knowing when they can get another child into trouble. Beacuse you, like me, take these normal and not major childhood incidents seriously other parents and children feel the need to tell you about them. Also their mum always believes its wrong doing against her children and believes them over anything and has led them believe anything that hurts, bad happens to them it someones fault and not just part of life.
The past 6 months I have taken to taking DS home when it's yelled they hate him and don't want him here, saying, 'thanks for telling me' to any tales, and mostly when they say 'DS has been mean' asking friends children what was said and then asking DS. Usually they have said something to him and he's said he's not playing with them if they're going to be mean - and they cannot deal with this. I say what consequence do they think they should ALL have!!
What I'm trying, and not very well, to say is relax. Stop taking every normal childhood incident seriously, ignore them. Children will get fingers trapped in letterboxes, paper will blow off the table, they will get hit by random objects and they won't always do what they're friends are doing after school.