Getting over your first love?

Elora
Sorry if this post is long and I'm sorry this is random but I literally have no one to go to about this. 
I've only ever had 2 serious relationships. My first being my first love, and then the one I'm in now. I've been with my fiancé for over 2 and 1/2 years now and the past few months I can't help but think about my ex. I love my fiancé with all my heart and we're expecting a beautiful baby on December. I would never leave him. But I can't help but wonder at times what would have happened if I stayed with my ex. I actually wonder as well if your soul mate and love of your life can be two different people. (If you believe in that sort of thing). My heart stings constantly tug and make me think of the past and it hurts so much. I honestly believe he is my soul mate and that's why I feel like I'll never get over him. I've been very tempted lately to reach out to him just to be friends and have him be in my life. And I feel like the shittest person in the world for thinking about him when I have a wonderful husband to be. Is this normal or am I just an asshole? 😕😢