“Please help! My sister got impregnated by a married man”

"Please help! My sister got impregnated by a married man"
From a female blog reader:

I believe you are all fine. I have a sister, she fell in love with a man without knowing he was married, the guy made it a secret, recently she found out she was pregnant and she was happy because she really loves the guy.

Yesterday morning we received a call from a woman saying that she should leave her husband alone or she will kill her. My sister is afraid and we are all confused and I don’t want to see her hurt. She wants to abort but I don’t support her with that.

The problem is why did the guy hide it from her and made her pregnant, he is a nice guy, caring, supportive and financially stable.

Advice us please, these men shall go to fire.