Try to help me here, please?

So my boyfriend and i have been together for over a year now and i truly think he's amazing. He's not only my lover but he's a best friend too. Thing is, i'm really afraid i'm gonna screw things over. How? Well lately... not lately but for a while now, i've been thinking alot about my ex. I tell myself i'm just missing him (cause he was a bestfriend to me too) and now i hardly see him. Well when i think about it, i really miss him and i start to cry... hard. I only talk to him online. I just don't wanna eff up what i have... but i can't let go of this feeling either! Steer me in the right direction here ehhy? What does this sound like to you?