I need help

I got pregnant in February and found out in March. My sister in law was so angry and jealous of me, that she told me I was a slut for getting pregnant before 25 and that she was gonna do everything for my children to die because I was gonna be a bad mother just like my mom. I immediately blocked her on everything! I miscarried in April due to my mom hitting my stomach. She got pregnant in May she is due in February and is 18 years old. She purposely sends me pictures of her ultrasound and belly saying that I will never experience past 3 months of pregnancy because my children are going to die. I blocked her on everything and she makes accounts just to send me stuff. When I go over to my partners house (she lives there) my boyfriend and me talk about ttc again. Somehow she stalks us and then loudly says "stop trying, your children are always gonna die" I am honestly super jealous that she is pregnant and I'm not. I need advice on what to do. Sometimes I wish she would loose her baby so she felt what I'm feeling. I know it's wrong but I can't help it when she says and does things to make me loose my hopes. Please help.