I don't know what to do about my boy problems!?

Okay, so my boyfriend (lets call him Cam) of 8 months, is the best. We've had some rocky time but our relationships so strong we've been through so much. Today on Facebook, his friend (lets call him Brandon) apparently was looking through my pictures. He commented on one of them saying "hmmmm haha" i said "hmmm what?" he said "i dunno lol i cant say what i wanted to put" so then he messaged me and started flirting. He was saying how i probably dont like him but he thinks i looked good in the picture. And apparently he found out about the time when i called him kinda cute at his and Cam's baseball game. He then said that it was kinda awkward we were talking because i have a boyfriend and he doesnt want Cam to hurt him. But i really dont see a problem with talking to him because no one could ever make me change the way I feel about Cam. (btw Cam knew all this was happening because i was telling him what I and Brandon were saying) Now, me and Brandon are texting...and he seems kind of interested. I know i dont wanna go out with him and i do not wanna seperate from Cam. But I truly think Brandons really hot and I've even thought about him being my boyfriend a few times. I KNOW that i do NOT want him as my boyfriend however, and I should stay with Cam. But i dont know wether or not i should tell Cam how Ive been feeling. He tells me everything...and I feel really bad about keeping this from him...but i dont want him to get mad and break up with me because he thinks i have strong feelings for another man. What do I do?!?!?