Pregnant by my sister husband

I go to my sister house every day to chat with her ,,then she got sick was in hospital from a car crash she was in for 3 months ,,, So I started to go cook her husband food for him we chat most night then one night he kissed me and i did not stop him then he took me to the bedroom were we had s** all night that was start to us have s** ever night then week before my sister was due out went see my doctor who said i was month pregnant but i did tell my sister husband