Please Please help me!

Hey, I am Pari from India and I am a teenager of 18 years. I am in a long distance relationship from past 5 years i.e, 2013 I have completed my 5th year on 11th April i.e, 5 days back. Now I am coming to my problem. The problem is actually about my boyfriend and a close friend of mine from whom I dont talk now. She was a really good friend till 4 yrs back. Actually what happened is when I came to this relationship I made my friend and my boyfriend talk to each other but now it seems that my boyfriend is more closer to her than me and the problem is that I don't like the both of them talking because my boyfriend use to flirt a lot with my friend and I told him not to talk to her more than 5-6 times but he didn't listen to me he use to hide and talk to my friend and whenever i use to know about them that they are talking he use to say that " There is nothing between us and I only talk to her because we are in a long distance relationship and as she use to live behind you house I can spy on you". But they use to talk about kisses and all that ****. I don't know what are they upto I only want them to be apart and I don't want my 5 years relationship to break up I only want my boyfriend to not to talk to her at all because he is not listening to me. Please help me to know what should I do now. PLEASE PLEASE PLEASE HELP ME!