See that’s the problem. Why on Earth are you feeding this girl? Your own attitude is fueling the problem. Look, if an insecure person wants you to feel hurt, and you fulfill their wishes by acting hurt, then they win.
Why do you even care if SHE says that her boyfriend is better than yours? Is she the ultimate judge here? This girl doesn’t even have the confidence to have her own unique personality, and you’re worried about HER opinion? Who knows your boyfriend better? You or her? You’ve decided to marry the guy, so obviously you must have found him to be a compatible partner. Don’t waste your time worrying about her silly little opinions. That’s negative energy. Instead spend your time with people that truly respect you and work on either maintaining a distance from this brat or cut off ties completely.