HELP with boyfriend

So my boyfriend went on my snapchat and saw this guy had snapped me earlier. And then he went on our chat and saw that the same guy had sent me a shirtless picture of him and he saved it and I couldn’t delete it because he save it. Now my boyfriend is saying I am a hoe and I cheated on him when I didn’t. The guy snapchated me asking for a streak and I didn’t answer him. I just opened it. My boyfriend is saying he is going to break up with me now and I honestly have no idea what to do. Someone please help.