It's not as high as 43%, for a rough estimate take the number of outs they have (9) and times it by 4 to hit by the river (36%). So there is about a 1/5 chance of them hitting on the turn and a 1/5 chance on the river...if you are certain they are drawing to a flush.

If you give them bad pot odds you'll make money in the long run as long as you don't pay them off when they hit

Definitely don't wait and see....then they won't call your river bet if they miss and you'll never make money :P

Your BR should be able to handle them hitting every so often, as long as your mental state can Keep Betting!! For example, if you could see they were definitely flush drawing in each hand the higher bet that they call with bad odds the more you make in the long run. If that makes sense...