Hey guys,
I was playing in a live MTT the other day and I can't stop thinking about this hand. I'm by no means any sort of great player, but I'm learning and would appreciate some feedback. Really let me have it.

I don't exactly remember the exact stack sizes but I'll try to reconstruct the hand as well as I can from memory.

I was UTG + 1, Blinds 500/1000 my stack was about 50k
UTG folds, I raise to 3k with JJ
Get 4 callers, including SB, BB folds. Pot is now 17k
Flop comes KKJ
SB checks, I bet 10k. Everyone folds to SB who calls.
Next card comes 8c I believe. SB checks. I bet around 18k. SB calls.
River comes Ace. SB shoves all in. He has me covered.

I tank for like almost a minute when the guy to my right calls clock, saying next round is in a minute and he doesn't want to pay increased SB lol.
I figured he could have AA, AK, KJ, KQ, K10, or air. Didn't occur to me he might be calling me with anything else. He hadn't really been bluffing. I end up reluctantly folding. He show Q10. I think about killing myself on the spot.

So, what do you think? Was I overthinking it? Was that a snap call and I messed up?

only on the river

You said he could have AA. I would eliminate that possibility. There is already 15k in the pot when it gets to the SB and you think he would just call with AA?
Come on man.

You have to call because too often he will have Q10, KQ, K10, even K9, K7s, K6s (called with good pot odds by the time it came to him).

And if he has AK (which he probably would have 3bet with pre-flop, or even 3bet shoved) or K8 (or even KJ which is even less likey cuz of your 2 Jacks), then you pay the guy off and move onto the next tournament.

Damn, you're right. Thank you. I gotta sharpen my thinking. I wasn't even thinking about how he acted preflop (obviously big mistake), I was making the false assumption that he was calling on the basis of the odds I was giving him.

yea we really block KJ, AA,KK,AK should be discounted as they are likely re-raising pre as they dont want to go multiway with the all action in front. So that makes alot of hands that beat us less likely. I would call here and if he has us beat than so be it

I'd check the flop. Give the opponents behind you a chance to start betting worse hands. Leading big only encourages folds. In a multiway pot, I'd probably check my whole range here OOP.

As played, never fold the river. Even players that play unorthodox or tricky will 3bet AA/KK pre when they are in the SB in a 5 way pot. There's just too much money out there and too many players to slowplay those here. I could see weaker players just calling with AK once in awhile, but it's still very rare. There are only 2 combos of KJ, 1 KK and at most 6 combos of K8 (if he flats those pre).

Even when I include AA/KK/AK/K8o in villain's range on river and leave out K2-KT, (KK+,AKs,KJs+,K8s,QTs,AKo,KJo+,K8o,QTo), you should still call. JJ still has 57% equity. In reality, you probably have over 90% equity, even when he has 0 bluffs in his range. You only need around 20% equity to break even on the river, so you have to call.

Also, if you think the player called the clock too quickly, I would protest to the dealer. He even told you he was only calling the clock because blinds were going up. If you had already taken a lot of time in this spot and his calling the clock was reasonable, that's one thing. If he called the clock quickly only to angleshoot, that's bad form and you should have the dealer protect you in these spots. Sounds like this might have seriously affected your river decision. 1 minute is too early to call the clock in a spot like this where you are making a river decision for your tournament life IMO.