top set vs straight & flush board

I played the attached hand a few days ago, and can't decide if giving up on the river was a mistake. I did not see a way to indicate this in the HIT, but note that the UTG had straddled for 5, which made me first into the pot with my raise. For what its worth, I had seen UTG play a wider range of hands than our standard ranges.

When the person to my left 3 bet all in, and UTG cold called, I did not take the time to calculate that UTG's all in represented more than a min raise, which would have made a 4-bet possible. I knew I was closing the action vs two opponents, and would be in position for any future rounds of betting, so I just called the 3-bet. In hindsight, I think a 4 bet would have been a better idea. Let me know your opinion about flat calling vs 4 betting here.

I was quite happy with the flop, and that my 2/3 pot bet was called. The third heart on the turn concerned me, and I checked behind. The river left me looking at 3 to a flush and 3 to a straight on the board, and when UTG shoved, I tanked & gave up.

As I kept replaying the hand away from the table, I started asking "Would UTG cold call a 3-bet for 10% of his stack, out of position preflop holding KQh, JQh, 78h, 79h or 89h?" (or maybe even 89 offsuit, as it seems a lot of people at 1/2 play a lot of offsuit connectors). Also, would he do this with the original raiser left to act? It seems like there are a lot of people in 1/2 games who play wider ranges, and for larger portions of their stacks, which is what made this difficult for me. And UTG did in fact cold call off 10% of his stack preflop, out of position, with original raiser left to act, with what we could consider a spec hand. Is this less significant since there is more leeway when speculating with pocket pairs than suited connectors? As I sat at the table, I could not get my mind off the fact that I couldn't beat a flush or a straight, and that you have said that in general in 1/2 games, a river bluff is unlikley.

I think a preflop 4-bet would have been better because it would have further narrowed his range, plus it would have made it easier for me to justify a C-bet all-in.

Also in hindsight, as played I suppose the SPR on the flop being 3:1 would support never folding, so I should have just shoved on the turn?

Please provide your thoughts on hand as played, and what you would have done differently.

Thanks