to be upset cat attacked neighbours cat?

[Lostandlostsomemore]

Husband thinks this is what cats do and nothing you can do so don't worry but I am!
I have a 6 year old boy cat, very much an outdoor cat and pines when kept in for too long, although we do make him stay in at night as live on quite a main road.
He was my grandmothers cat before she passed and very used to being able to roam and he won't use a litter tray of any sort so can't keep him in.
He's been the only cat on the street since we took him in 4 years ago so no problems.
Anyway new neighbours moved in 2 months ago, 2 boy cats who are also very much outdoor.
She works full time as does her hubby so they are out all day and some nights.
They aren't like ours who will approach you / anyone to stroke them and when she moved in she said " mine hate other cats coming in their garden so I hope he doesn't push his luck! "
I've seen him try to sit on their shed and they his and him so he backtracks and I've seen him have a fight with the local ginger cat when he's come in our garden but morning major.
Tonight I can hear hissing etc and go out the front not the garden and they are pulling each other to shreds.
Our cat has a bleeding neck and hers has lost fur and his collar is broken.
I got our cat in but she was at work so waited until she was home then knocked and told her / made sure her cat was okay.
I said I didn't know what started it as wasn't in either garden so not territorial and she replied " yours probably attacked him. He sits on our windowsill pawing and hissing at the cats through the glass " I said I didn't realise and she went on to say that he has attacked her other cat a few weeks back the day after they moved in by going into her garden, her cat hissed and mine pinned him down and bit him :-(
She said since then he won't go in her garden ( which I'm glad about ) but that he is very boisterous.
I tried to keep it light saying it's worse than having a kid of 5 ( I have one! ) as I can't keep him in and she said no cats are cats what can you do and hers hate other cats etc etc but then dropped in that her cat hasn't eaten since she got home so might be in shock.
She's really hard to read, quite stony faced so hard to tell if she's joking even when she says things that sound like a joke.
Just feels awkward now :-(

Cats will be cats the ones next door are interlopers into his territory, the cats will sort it out amongst themselves, there is nothing anyone can do except stand by with the antiseptic when required.
Give it a wee while and the cats will have "established boundries"

She probably was stony faced. Even though she knows it's what cats do, she doesn't need to pretend to be pleased about it. The fact that she hasn't approached you to complain shows she knows there is nothing to be done. She's upset, you're upset. The cats will sort it out eventually.

Ferrel?! Don't be ridiculous
He's a cat not a kid

Cats will fight to establish their territory and heirarcy. One of mine is the alpha cat in our street. The black cat next-door-but-one is allowed in our garden, but the ginger cat from over the road isn't. They sort it amongst themselves and it settles down until one decides to make a bid for alpha status.

My old male cat regularly got beaten up when we got new neighbours with cats, he was a trier but always seemed to come off worst, cue many trips to the vet - luckily he was insured although you have to pay the excess. I wasnt happy about it but thats what cats do.