The thing is when people get a bit butthurt they react very badly and struggle to admit they are wrong and apologise.
There is an interesting book called dont sweat the small stuff in love, and it talks about apologising even though you know you are not wrong so you can stop or reduce your own stress with a situation.
He should never have thrown the ball with malicious intent, but he may not have meant it maliciously but didn't realise his own strength or that you weren't looking. (But none of us know the intent or meaning because we weren't there or know your dh)
Similarly if he got upset over you squirting him with water or calling him a dick (even though he probably deserved that) then you should probably apologise for your part in the fall out.
If this is not usual behaviour for him or more extreme than normal then maybe be the first to apologise may help? You can be the bigger person if you do truly love him
I struggle to apologise even when I know I am wrong, my dh knows that it's a flaw I have but I really try to do it or show I am sorry in another way.
My dh has hurt me in the past because be forgets his own strength but I know there is no malice behind it just him being stupid (mini roll hitting me square on the head still comes up every so often)
To me his reaction is like I would react If i knew I had done wrong but didn't know how to apologise or explain my actions.