My boyfriend got me and my 19 years old Junior sister pregnant, what do I do should I kill him?

Unfortunately, the pretty girl you see above has just complained that her boyfriend has been sleeping with her junior sister who's is just 19 years, and the most disgusting part is that she (the junior sis) has had 5 good abortions for him and she had 3 for the same guy. She said she has been loving and trusting the guy (her boyfriend) until yesterday when her kid sister confessed the situation,

"I was so ashamed of myself, I feel so stupid, used and abused, it's like stupidity runs in our blood, was it his d*ck, his money or his sweet mouth that made us this foolish? Because Even my kid sister said she doesn't know how she got involved with him... "she said 

And she was now asking the best thing to do to this guy, whether she should cut off his manhood, set him up and get him arrested, or make him mad?  And the only thing she don't want to hear is" forgive him"

Please what's your advice on this case...?
Comments please

Source : @Fame_house