A little advice please

So I have a family member who is in a relationship with a pervert. This man has cheated, lied and was even found guilty by a court of law for 2 counts of battery for touching. Minor ( court is still pending) however she continues to stand by his side. She doesn't care that their children are facing the finger pointing and names. So my question is this.....should I continue to avoid them like I have for over 4 months? I just don't want my kids having to deal with them same stuff the other kids are