Confused about certain feelings

I met my bestfriend in 6th grade. We dated a little and this was back in the day where his parents wouldn't allow him to call girls. We decided to be friends for awhile after that. Through middle and high school we spent so much time together but always dated other people. We were never both single at the same time. Until summer after graduation. We didn't date we just decided to have sex. He was really Christian and wanted to give his virginity to me since he knew he would never regret it. Well that happened and after that we just remained friends. I met my now husband and he met a new girl. I worked with this girl when I was 16 at a movie theater. I was happy he found someone to make him as happy as my husband made me. Well fast forward my husband and I get married and get pregnant. Two months later they announce their pregnancy. My emotions are confusing me. Idk why I even let it bother me. He's not my husband. I love my husband. But why do I feel like we are having babies with and getting married to the wrong people? I haven't spoken to him since I told him I was engaged. I know I sound like a terrible person but I have never cheated on my husband or ever thought about it. Yet, why am I jealous or why am I second guessing everything?