I'm such a terrible person 😭😭😭😭

Gracie!!! πŸ’„πŸ‘›πŸ‘  β€’ In Love ❀️,
     I love my fiancΓ© with all my heart. But our relationship is complicated. We aren't the "regular" couple. We can't go out, to restaurants, movies, no where. We've been like this for 3 years. He comes to my parents house, or I go to his house.
    I met a new guy, he is so adorable. Such a nice guy. We started spending time together. He tried to kiss me but, I wouldn't kiss back. Idk a part of me knows I shouldn't do it. But another part of me says to give him a chance. I made a terrible mistake by telling him, that I'm single. He asked me to be his gf  but I told him I needed time.
       I don't know what to do. I'm so confused. I love my fiancΓ© and I don't want to hurt him. But sometimes I get tired of him, I feel our love is fading, I feel like I'm just there because I know how much he loves me. &&&  as for the new guy, I feel happy with him. But I'm scared, if I'm with him I would lose the other. What if with him it's just a few months when I had already something serious enough with the other. 
    Sometimes I think, why not both? It might work out for a few months but they will find out eventually. Plus deep down I know it's wrong. 
     Please help me, I need advice. I don't know what to do 😩😭😭😭😞