I terminated my pregnancy as my baby had trisomy 18

After 5 years of my marriage and through ivr, I finally had my boy who is 2. So I thought I am not so easy to get pregnant. Who knows, I got pregnant when I was not even trying. Everything seems smooth. Had all the pregnancy signs. However, after multiple tests and scans, my baby girl was having trisomy 18. The fetus specialist says only one side of the heart was functioning and there were other issues with the heart as well. So even if we give birth to her, no surgery could help. We finally decided to terminate the pregnancy. The process was so scary especially when I felt my girl drop out of me... its been several months. though life goes on, nobody knows the pain that remains in me. I keep thinking is it my sins that cause my girl to be so sick....