What happened to family comes first?

Family means everything to me... but apparently not as much to some people. There is someone from my past who royally tried to ruin my family, tried to finanically destroy my husband and I. And now two people in our family (one on my side-and one on his) are STILL speaking to this person, still friends with this person, and still want to hang out with this person. Whatever happened to loyalty? What happened to family comes first? I guess this is one of those things in life I'm not ment to understand?!