It's a shame that your wife left you for someone else, but it's completely worse that she went for your sister, who is also in the wrong. I wonder how long this affair went on before you were told. They both lack major morals and common decency. You don't deserve either one of them in your life since they proved to not give a shit anyway. I'm sorry you are going through this. Stay strong.

If they get married at least you can say you’re related to the Scissor Sisters