This one is plain and simple, ignore the people who are talking crap, and if you’re the one causing it? SHUT IT!
You are happy with who you are, if there is something your partner is hiding, it will come out. It will always come out.
People, whether you think that person is wrong for your friend, or you don’t like your ex’s new partner, keep it to yourself… unless you have proof and know for a fact that they are bad.
Gossip is annoying and don’t go off telling others, you are not in that relationship and you don’t need to be.