If you have all the information, you should be winning

This past weekend, I played poker and was in a hand where I made a flush and thought I was ahead in the hand until another spade came and then I thought the other player might have made a higher flush. He bet and I decided to call his bet and see what he had. I was right, he had a higher flush. I was right—and he won and I lost chips. 

If you’re right, you shouldn’t be losing. If you’re right, you should be winning. 

I should have cut my losses and not called his bet. I should have folded.