I don't get what would be scary about the turn 5. Would he be betting out with a gutshot draw on the flop and call a raise with it? if a 7 or 3 hit, then I could be a little more concerned since that could complete an open ended draw with 57 or 35. I would have to bet that turn either way as I can't be looking for him to have whatever hand that can beat me. That said, I like how you played it but I think you are over analyzing this one.

The good thing is that you thought through the hand properly. Unless he's a complete idiot, he does not have the straight. betting out small into a preflop raiser, then calling a decent raise with something liike 78, is almost immpossible to fathom.

Which makes your river call a hell of a lot easier