This sounds similar to my current situation. Well, ok, not exactly. My DH and I had ttc for over 3 yrs and (didn't yet pursue the IVF or any FD) but got a BFP on Christmas. My sis in law has 2 children of her own and doesn't really take care of them. I was so angry when she concieved the second child because when I kept her first, there was a sore on his testicle the size of a pinhead and I got it to clear in a day just by regular diaper change. What does that tell you? Well, every since she found out that we were expecting, she has been saying things like "she's going to kill herself" and stuff like to keep me stressed out. I think she may be trying to make me loose the baby? I finally blocked her on IM b/c that is where she is saying this stuff.
Sometimes, you have to just let the ignorance of those stupid people leave you and know that you ARE RIGHT AND THAT PERSON IS STUPID AND WRONG!!
God will bless you all in your journies to ttc.