I don't think you can fold once you bet the flop that size given money invested and how much you have to call it off.

That $4 bet is way too big unless everyone who called is a fish. I like to check or bet small around $1.50~ on the flop, probably check 4-way as sets are well within their range.

These suck sometimes. If you bet big and get shipped on you're stuck calling, if you chk they all chk behind so many turns will be death cards.
Big problem here is the board is what I term 'middlish' which hits nearly everybody in the kisser.

For me it's a chk flop and give up if they bet too hard. Nasty but not unusual at nl10 so not a monster fold mob handed.

4 way here, I think I'd check. On a wet mid board that smacks 99 and JJ, as well as other draws. I'm of the opinion that it's just a horrible spot being 4 way in the first place. Sometimes we might actually end up all in multiway when the pot gets huge and then we have to just hope we can be ahead or hold. I think best just see how the action runs by checking, but I agree with Harvie and Pwll, you're invested now you've bet this big so yeah you can't can't fold.

Unfortunate spot, and in-game this is never easy.

I'm not folding as played. But if you want to c bet I wouldn't make it any more than $2 at most. As Harvie suggested checking is a good option too.

If you do make a small c bet here I'm probably making a controversial fold in a 4 way pot. Just too many sets and two pair combos, and even the draws have good equity so we're never really crushing once we call it off.

The c bet is way too large here , bet small like everyone says or c flop

I agree with the general opinion your Cbet was too big.
Why did you bet that big? (Genuine question not trying to be a smart arse or anything).
I play 10nl and have standard bet slider
c-betting of 65% / 80% / pot.
My standard line at these stakes is 65% and the 80% is reserved for the whales (generally).
I thinking checking here on the flop is a big mistake at the micros.
In future I would suggest not posting the result and the villains hands (we've all done it in the past).