What to do about the ex i'm still in love with?

so, my ex..let's say justin..i pretty much never got over. he was the first guy i had with. this is what gets me too is that hes been my ex for 7 years. it seems like whenever ive had guy problems in the past he comes around again, its pretty much the only time we talk/hang out. i've been dating this guy, let's say chris, for a year. we broke up for a few weeks for multiple reasons i wont get into, but we've been trying to work it out and we're back together. since we got back together it seems like things between chris and i are even worse because now he doesnt live with me. i've been debating leaving chris because of the way he treats me and always puts me last. if chris and i brake up, i'm pretty sure justin and i are gunna get physical again like we always seem to. justin isn't a notch on the bedpost type of guy either but when were together we just sort of reminisce on how we use to be, he constantly flirts with me, he holds me tight, makes me feel safe and i almost feel like he loves me back but is too scared to let anyone back in since his last horrible break up. i know thats how he feels because he tells me its better not to let anyone get to close because it will always just end in heartbreak. i have no idea what to do or say to justin..i wish i could just tell him but im too terrified of what will happen or how he will react..i am desperate to have him be mine again but i know hes not looking for a relationship, and if i tell him how i feel i dont wanna scare him away and chance ending everything. 7 years and i still think about him almost everyday..help.