my sil is preg and im pretty pissed. she has a son by my bro (not her husband... her sisters…

my sil is preg and im pretty pissed. she has a son by my bro (not her husband... her sisters husband), and a girl by a married guy (who has 9 other kids)... and she sees him every 15 months, and yep, she got preg by him again. she wasnt even trying.... and here I am praying it would happen and it didn't. im destroyed inside.