I dont think its that bad without a read and I realy dont think its a 70$ mistake. Lets say it might be a 15$ mistake for a bump min raise at the end.

Flop, feals like some sort of draw (from both you and him).

Turn, you bet strong when the flush hits and all he has is 7 high. It feals like he is scared of a higher flush with the rather heavy calling action on the flop.

River, not a funny 3 but kinda weak raise, like he is trying to control the showdown or gain some info.

But then again, he did complete the blind with 73s. This is why you need those reads. Time to make some notes.