I(30F) found out my fiancé(31M) was cheating on me throughout our relationship. Advice on what to do?

I've been engaged for the past six months, and before that, we were friends for about six months. Recently, I discovered that he was with his ex-girlfriend throughout our engagement, and he didn't tell me himself. Since finding out, he and his family have been urging me to reconcile. They're offering to pay for the entire wedding, promising me full control and making other assurances. His friends are also trying to convince me that he's a good person. I'm seeking honest advice on whether he's likely to change after marriage. Has anyone else experienced a similar situation, and what was the outcome? I come from a South Asian background, where breaking an engagement, especially for the woman, is taboo.