My sister had a miscarriage and now I’m pregnant ...

So my sister has a couple of children already and a few months ago found out she was 6 weeks pregnant. (Past story : I’m 10 months pp and when I found out I was pregnant with that pregnancy she had just had a abortion and obviously was very affected by me being pregnant , she barely came around me and didn’t even see my baby for the first few months ) anyways then at 9 weeks pregnant she found out the baby had no heartbeat. So she had to have a d&c and it was very hard for her. Now fast forward I just found out I am 5 weeks pregnant. She had the miscarriage a month and a half ago. I am terrified to tell her. Idk what to do. I feel so bad for her and I know she will act happy but then actually be upset.