I Need Help With My Boyfriend?

My boyfriend has a business trip at the end of this month, its for a week, he is stayin in a hotel 2 bed apartment, but my problem is that there will be 2 other guys and a promo chick, she is paid to wear next to nothing and to be a flirt and tart. She is staying with them for 4 nights. He has to attend a moto expo and one of the guys, that is staying with him, only hired her for his benefit! I need some advice.. i trust him but we're only young and i wouldn't be too surprised i something did happen... We do have a child together, we have been fighting about it a little, but i just dont like the situation.. What can i do? Help me though this please!!!