My new kitten hates me

About 10 days ago a skinny little tabby kitten came running up to me like he
knew me his whole life (8 months or so). He wanted to be friends so I took
him in and he took to my place very quickly. My other 3 cats were pretty
cool with it though my 2 year old female cat put him in his place often. He
seemed to take it as well as could be expected.

So last Saturday my big adult male cat Jack got all worked up seeing a stray
cat in the yard. He huffed and puffed trying to push through the window
glass then assaulted the youngster and beat him up pretty badly. Tonight I
called the vet because he was not coming around. He is depressed. He
doesn't want to socialize or play - not even the squeaky mouse toy which he
could hardly put down before this happened. They found a small abscess and
drained it and treated him for ear mites. Also took blood for his tests.
But now his personality is completely gone and has been for 3 days now.

Well things have gone from bad to worse. He wants nothing to do with me and
tosses a fit when I try to pet him. He growls and hisses fiercely at me
when I pick him up. He truly hates me. He is seeing me as a threat and an
enemy. He took the vet visit fairly well, though. They had no trouble
handling him and he was quiet the whole time. But now here at home, he
wants nothing to do with me at all. I just gave him his Amoxy drops and he
tolerated it but the howling and hissing was breaking my heart.

I suppose he must be a sensitive little guy. He is not as resilient as most
other cats I have known and kept. Is there hope for a reconciliation? Do
these things become permanent and they hate you for life? He just is so
depressed and miserable and now so am I. For now he has a comfy room all to
himself with food and a litterbox and soft places to sleep. I've just never
known them to be this way for this long, a few hours sure, but not 3 days.
Granted we have not bonded and he's only been with me for less than 2 weeks.

Thanks.