Is it normal that i am unhappy and in denial?

I already post my first story here where my boyfriend for three years. So here it goes I and my boyfriend broke up last Sept 3. The feelings changed a lot when I used to went back to my hometown that was August 16 this year. The main reason why I went home its because I want to rest and unwind since I've just undergone a treatment for my illness. At that time when I departed I used to meet someone. He's simply amazing,gorgeous, kind and down to earth. As I've observed this guy is really an opposite of my bf. He's mature enough and can handle things more smoothly. The very first time when we talk I feel something special towards him as if I've known him for a long time. He assisted me everything during the travel since it happens that we're boarding on the same ship. Starting that night we have a long talk, we never slept at all until the ship reaches the port of destination. I told him i have a bf already and he just smiled. He even asked for my number and I gave it to him without knowing that its the start of everything. We communicate with each other until I get back from my hometown. My boyfriend noticed that I'm acting so cold since I arrive from vacation. I don't know but it feels like I'm really confused with the situation, everything changes. My feelings for my bf, the way I treated him is not the same anymore coz I'm in love with the person whom I met on my way home. Until I decide to tell my bf that I need space and it hurts a lot to see him crying so helplessly that I don't know what to do. He asked me is there someone you love? I said no for the fear that he might ruin his life which is exactly what he's doing right now. Everytime he calls me nowadays breaks my heart into pieces. I feel so devastated upon knowing what he is doing with his life now. He even indulge his self to smoking, drinking etc. I'm with Dennis right now the person I met he loves and cares me and understands me the way I always wanted. Maybe the reason why I broke up with my bf because I'm fed up of his childish attitudes and I'm always the one who is adjusting, and understanding his tantrums that it made me lose my mind. I'm happy with Dennis but deep inside of me I want to do something for my ex. He's being miserable right now. Everytime I think of him it makes my eyes look sorrowful. Is it normal to feel guilty because of what I did or he just chose to be miserable? He wanted to get me back but I can't. I have dennis and I love him. Is there anything else I can do to lessen his misery?