Preflop
Standard defend. Before we even get to the flop, its important to notice, that you are almost 300BB deep with the preflop raiser. This is definitely going to change the range, you should be willing to stack off with postflop.
Flop
Very good flop obviously. 74 and 42 flopped a straight, but neither opponent should have that in their range, so you essentially flopped the third nuts. I definitely agree with a check-raise, but your sizing is to small. After you call his 6c bet, pot is 16c + 3 x 6c = 34c, and you only made it 12c more to go. This mean, you are only betting around 35% pot, and you dont need to give 2NL opponents such a great price to get action. I would go to at least 30c here, and honestly you can also hit the "pot" button (40c) and get almost the same amount of calls.
Now however the preflop raiser puts in a 3-bet, and this definitely change my thinking from "I have the best hand" to "I could possibly be coolered". Its possible, he might be overplaying an overpair, so I am not folding. But I am not putting in a 4-bet either, and this goes back to the fact, you are almost 300BB deep. If you were 100BB deep, then set over set is pretty much just a cooler, and we should not worry to much about getting stacked. But for 300BB its different, so you definitely want to just call for some pot control and stack protection.
Turn
This is not the greatest card, because now JJ also beat you, and 77-TT is probably slowing down and not betting again. But he does go pretty small, and maybe he can still have QQ-AA. Those
hands were probably more likely to 3-bet the flop than 77-TT in the first place. You are also getting a good price, so I would also call again but definitely not raise.
River
Now you also lose to QQ and random backdoor diamonds, if he somehow has that. He bets half pot, and this is a genuinely tough spot. On one side I honestly dont know, what you are beating here? Is he really still betting AA or KK or such a scary runout? Probably not in my opinion. On the other side you are getting 3:1, and sometimes people play pretty weird in the micros. So I would most likely also stick in a call, but its definitely more of a crying call than a call, because I am loving the spot.
Results
So he coolered you with a set over set on the flop. Overall I think, you played well and lost the minimum. The only real mistake was raising so small on the flop, which ironically helped you save some money this time.
