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Yang asked a question

My boyfriend told me he went out with his friends but didn't tell me who all. At night I see that he's getting tagged by this girl in several videos and they were playing basketball together. When I confronted him he's saying that his friends were also there but I never saw his friends in the video. Then he told me that I don't trust him and didn't defend him when other people told me so it's my fault. Ugh I'm so fed up what should I do?