I Have a Confession

I know it's wrong to have feelings for 2 people. I'm more honest than most people, and I think it scares my significant other. I also think he's starting to not trust me as much because I've been so honest about my feelings for this other person. He just has to understand that I am not going to leave him. He has done nothing wrong. But what am I supposed to do? Hide the fact that I have linguring feelings for this other person from my past? It would drive me insane, and the reason I came clean about it was because I couldn't keep it bottled inside, and feeling guilty about it. It's like I did something wrong. It's like I stole something. Of course I didn't, but I can't keep things like this hidden. And now he's questioning what I feel. I've already told him it's not something I'm proud of, and I can't keep going on with it on my back. I really want to burn it out of me. And the other person has lost their trust for me because I tell my significant other everything. He feels like he can't tell me anything now. I don't know what to do about that, because I can't give up on a friendship that goes back to my teens, even though that person was off the grid for 8 years. My significant other and I built a relationship on trust, so that's how it has to stay. Otherwise I'd be lying about being honest. And there's no way I'm going to give up. But how am I going to solve an issue that I created unintentionally? How many times do I have to say I'm ashamed of how I feel, and that I need to talk about it? How many times do I have to explain how loyal I am, and that my intentions are purely about getting through this without hurting anyone?