Guy insists I cut the line? who was right?

I was waiting in line, when I was the last in line however a lady turned in her light and told people that whoever was in line next can come over. Now the guy that was next was so close to the people paying 1. It didn’t look like he was next in line 2. He wasn’t paying attention at all. I gave it a quick moment for him to pay attention and then got into the lady’s line so I can pay immediately ( I had one item) the guy yells “I was next in line” meanwhile he has a pile of items and insisted I cut the line because I actually paid attention to the lady. Was he being a douche or was it rude to go ahead in line?
Guy insists I cut the line? who was right?
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