Am I the at fault when my ex-girlfriend cheated on me with my uncle?

She is currently pregnant with his baby, and now my aunt is mad at me for courting a woman who was capable of destroying a family. My cousins are also hurt because of this.

The reason why she cheated was because she told me she wanted to have a more extravagant life with a man who could spoil her more, claiming I wasn't able to do that because all I do is cook for her and clean her car. She also told me that I was boring her whenever I talked about charity work and religious (Christian events).
Am I the at fault when my ex-girlfriend cheated on me with my uncle?
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