Am I wrong for being mad about this?

So my sister is pregnant AGAIN with her 4th kid. She only has 1 of the 3 she already has. The first one by mom has and the second one was adopted. She calls me the other day to tell me she's pregnant and she's going to get an abortion and let the baby's dad thing it was a miscarriage. I would also like to point out her oldest kid is only 4 and the youngest is 10 months. My husband and I have been TTC for a few months so I'm having a hard time being supportive of anything or even being there for her to complain to. I just want to shake her and scream...