anyways, Bean is here to help with her cruddy advice!
First off, you need to tell your boyfriend clearly that you weren't cheating on him (why would you be dating him if you were?). Make yourself very clear. Ask him why he thinks that.
Try to work something out with him, but if you can't then get yourself a hot chocolate and call it a day. Why would you date someone who thinks that you're lying to him?
"We don't decide who lives and dies. Not down here."