I had premarital and got pregnant but am not with that man anymore, so what does this mean for me?

When I was 17, I fell in love with a guy who was a year older than me. He told me he loved me after a few months of dating. Just before my 16th birthday, he convinced me that since we both loved each other, we should take our relationship to the next level and have . I, being a naive teen, went along with it because I truly felt that I loved him. Our relationship went along just great until just a couple months after I turned 17, I got pregnant. He was somewhat happy at first, but then, in the middle of my pregnancy he became distant from me. He had dropped out of school and moved out of his parents house and in with some friends. I however, stayed home and kept going to school. I even started going back to church after not going on a regular basis. I had the baby without him at the hospital. He did come the next day and then took me and the baby home and helped me out for a couple weeks. After a few months, I found out that he had been with a lot of other women while I was pregnant and was still dating one of them. We were planning a wedding and my dress was almost ready. We parted ways and I saw very little of him. When my son was 2, I ran into an ex boyfriend from when I was 14. He said he still thought of me and wanted to get back together. He loved my son from the beginning. We were married in the Catholic church, which is where we both went when growing up. We have now been married for 5 years and are expecting baby #4, and he does include my son as his own child. What does this all mean. I am excepted in the church, but what does it mean for me. I know that what I did was considered a sin, but since I was committed to the first man in my heart, in the eyes of God, did that make us married? And since he cheated, did that break the bond and make it ok for me to be married to my husband now? I need some answers.