Has anyone stuck with the partner after he/she cheated on you?

I am a 27F and my fiancé is 28M. We are supposed to get married this December. He works in an all female team and he fell in love with one of his colleagues who is 26F. The female colleague is in a long distance relationship. I found out that they have been flirting all day in office and also on text. They have kissed and made out once or twice during their office parties (after having some alcohol). He has confessed that he is in love with her. We have been together since 7 years and stopped having sex since the last 2 years which has bothered me a lot. He always blamed my weight gain for the lack of sex in our relationship but it turns out it was mainly due to his 2 year love and emotional cheating with his colleague.

I want to break up but wedding plans have already been made, parents have met and on friendly terms with each other.

What has the experience been of people who have continued to stay with their partners after being cheated on?