Feeling resurfacing

I've been in a relationship for more than two years. A few bumps along the way but that's normal. I love my S/O and I am happy with my life, but recently I've had this weird feeling that I made a mistake. The person I was previously in love with (we never officially dated) is still in my life because he is still close to some members of my family. When he and I ended everything it was my decision. At the time I didn't know he loved me as much as I loved him. So I was upset, now I know he just wasn't good at talking about his feelings. I felt like the feelings were one sided and became upset. I told myself I had to let him go, forget how I felt and move on. He at the time went of into the military so we didn't see each other often but he did write. In his letter I got the feeling he was trying to tell me he wanted us to be together be he never openly said it, so I was a bit frustrated. I told him I wanted to move on. He slowly understood. I feel like I made myself move on because I didn't feel like I was getting love in return. It felt like I turned off a switch. I decided to let him go but I don't think I ever stopped loving him.
Now, the guy I am with has been asking me questions like "if I asked you to marry me tomorrow would you say yes?" He and I have said we won't be getting married any time soon in the past, I feel he asked only because we've gone to a few weddings since we've been together. But the questions kind of made me think. As much as I love him I know I never really let go of my previous love. I have no idea if he feels the same, he and I talk when he comes to town but he's still very reserved about his feelings. I don't know what to do or if I should do anything. Help!!!