This empty feeling

Sometimes when I talk to my boyfriend, I get an empty feeling inside my chest.

We've been on and off for the past two years and it's a long distance kind of thing. But he hangs out with this boy named Jake. And they dated a little while back (He's bi) and then Jake dumped him.

But after a while, they started hanging out together, right after me and my boyfriend got back together.

And I feel a little jealous because Jake's like his real life friend and I'm not. Because it's long distance. And whenever he tells me he's with Jake, I feel all empty and I want to curl up and die. Or at least cry my eyes out.

We've been on again for like a month now, and he's almost always with Jake. I mean seriously, there's hardly a time when he's not.

And I get numb and think 'what if they're doing something?'. And I don't want to ask him, because then I look insecure. Which I am. But I don't want to tell him because then we get into a fight.

Any advice?