I need help!!!!! PLEASE??????!!!!!

I like this guy, him and I are best friends and everything and I know he has feelings for me, but he also has feeling for my other best friend which is okay with me because they're both happy, but he was known last year for crushing girls hearts and then moving on to another girl, my friends are scared and don't want me to hang out with him because they think if he starts dating me he'll break my heart, I know it's not true because I know him better then anyone. How can I convince my friends to trust me and actually like him?????