What can I do

My boyfriend of 3 years was caught talking to another girl asking her if he can do a photo shoot of her makeup bc he liked it. He had a 4 day streak with her on snap chat. I was and still am extremely hurt. I considered that cheating. I feel so ugly. It happened about a month ago and I still can’t move past it, I need advice on what to do Bc I lash out so randomly at him about it. But they are my emotions speaking😞