falling in love with someone else..

I have been with the father of my dd for several years. The last few months I was nagging for an engagement to get married and have another child. Since we've been together for so long I felt tired of being stuck with him in the same place. I nagged nagged and nothing. Our anniversary passed and nothing.. come fall I met someone at a family reunion. I did not speak to him directly but I saw him and felt weak in the knees. I don't know what I felt.. idk if it's love at first sight or what. But I never ever met this person. What I felt that night when I saw him urged me to try to find him and dance. But I couldn't, and get as if wow I saw this person felt some type of spark and now I'll never see them again. I stayed up that night until 3am searching on my family members Facebook friends for his Facebook account. Which I found and added him immediately. The next day I messaged him asking "hey was that you at ____" and certainly he replied. But after a quick look at his pictures I noticed he was my cousins baby daddy. I immediately deleted him. Then start receiving his friend request and messages saying what's wrong?! And I made it very clear I cannot do that to my family member. I had no idea I didn't know. All I knew was that she had another boyfriend and that's about it. He tried to explain himself that he's not with her that they broke up about a year ago and I gave in. I really don't know if it is love at first sight but we quickly hit it off and for sometime have been seeing each other. I immediately broke things off with the father of my dd. I did find out my cousin is engaged to her boyfriend. But I really don't know how she would feel if she found out. From what I've been told what they had was a one night thing and they tried to make it work out but couldn't. She is part of my dad's family who has never liked me my mom or sisters for some reason idk. So I am nervous if she finds out I am with him and have been for a couple months now she will maybe hate me and say hurtful things. I don't know what to do I really dont. I just know I am in love with him and I have this strong connection with him. I tried to stop this and continue my life as if I never met him but it is so hard to go back. I don't feel the same. I tried and tried to go back as normal with my dd father but my heart and conscience won't let me. I want to do the right thing and stay where I was at before I met him but idk how to overcome all the emotions I feel. I just want advice or some piece of mind that I'm not the only one who has felt or gone through something like this.. I've prayed I've told my mother I don't know what to do anymore.