Super jealous boyfriend!

My boyfriend of 2 years is the ridiculously jealous type. He has always gotten mad over small things involving other men and me, including going off on me in public due to assuming that I was looking at a guy who I wasn't looking at, at all. I kinda snapped and broke up with him over things like that. He apologized we got back together and he stopped acting like a total dick. Well I have a best friend that is a guy, I've been friends with him for like 8 years and he lives like 3 states away. My boyfriend gets so mad when this guy messages me, he won't admit he is mad but I can just tell, mainly from past experiences, that he's getting jealous. I've gotten to the point where I find myself ignoring my best friend to avoid upsetting my boyfriend, which I know is probably upsetting my friend really bad, and upsetting me pretty bad. What can I do to make my boyfriend stop acting like this?