baby shower etiquette??

Amanda
I am having a huge problem with men coming to the baby shower. My mom and sister are planning it and my fiancé is coming to keep an eye on his sister who has a case of sticky fingers. She used to be heavy into drugs and when I invited her, she was completely sober; a changed person. Well she recently got back into drugs and I don't trust her enough to leave her alone without an extra set of eyes on her. Hence why my fiancé is coming... it's happening tomorrow. My sister doesn't like the fact that my fiancé is coming and I already know atleast one of my friends is bringing her husband. There was nothing on the invitation that says women only so I'm sure there will be more then 2 guys there. My sister kinda freaked out on me today because of my fiancé is coming and I'm not sure if I should do something about it. Does anyone have any advice or maybe something similar that happened to you??