He said this during sex

My ex and I were having a mind blowing intimate sexual intercourse and during that time he said, “I’ve never felt love like this in my life,” and then I stupidly said, “I love you.” He paused, sighed and continued. We had said ‘I love you’ to each other before, but bare in mind that this was a situationship (fading away at that time). What did I do wrong? Was my reaction wrong? Someone please help. That really was the BEST intimate romantic sex we both had ever experienced.