Family in law from hell

How should I react when his family compares me to the ex in my face during my baby shower ( I don't know why I feel this will be happening)? Also, how should I react when a family of his that wasn't invited to my baby shower but is coming with my boyfriends mother because the mom refuses to come w/o her? This uninvited person is the aunt that constantly take cheap shots at my boyfriend and I once stood up for him and she called me names and told me I was no one to interfere in their family.