Alyssa Renee Gutierrez, 23, from Las Vegas, met fiancé Peter, 57, on a dating app
Said they had 'instant chemistry' on their first date and quickly fell for each other
Peter proposed to Alyssa, making her stepmother to his adult children
The gambler's eldest daughter being just three months younger than Alyssa
Said they face constant backlash from strangers who brand her a 'gold-digger'