I want to know is it my fault?

My fiance after 7 year relationship.. cheated on me while he were in another country.. he came and confessed cheating.. he begged me and asked me for another chance.. he stayes with her 6 months.. and came to me while he was still with her.. i valued our years together and decided to give him a chance.. i told him you should choose betweern me and her you should choose now.. he chosed me.. but after that he changed all my life in a bad way.. he changed too... yesterday he told me in a message

"You should leave and let me go and if i back to you then i was yours.. you prevented me from her.. you forced me to leave her in a bad way she was ill "

He left me

Now i feel like hell.. i didn't know that she was ill... i just believe him.. trust him

Is that my faul.. my guilt?

What should i do?

I want to know is it my fault?
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