Devistated

We rescued 2 year old Sadie (a calico cat) from our local shelter a year ago. She was not easy to take in because she didn't know how to groom herself and she rarely used the litter box. This wasn't a huge issue at first more of an annoyance, cleaning and mopping everyday. Now I'm in my third month of pregnancy and she had been using my kitchen floor as a litter box for two months. She has ruined thw hardwood floors in three rooms in our house. We made the heartbreaking decision that we were going to bring her back to the shelter and hope that someone would adopt her who could train her maybe. When we did they told my husband that based on her issues they are putting her down. We have been sobbing all morning, this is so horrible. I feel so terrible for that poor sweet cat, but now that I am pregnant I can't risk it. How do we get through this.