When I first read your posting I started laughig out loud, because I saw much of my family in your words. I am of a hispanic family, born in Nicaragua but raised in the United States. I am very much American in my thinking but have experienced much of the hispanic way of living. Be assured that your significant other sleeping with her 19 year old son is nothing more than that. I have a brother who is now 17, but just started sleeping in his own room 4 years ago. Yes, my brother slept in my parents room til he was 13 (how they ever had sex is beyond me)! I know you are probobly thinking there must be someting wrong with the kid, but quite frankly there's not, infact he's graduating valadictorian and heading off to ivy league in the fall. That is beside the point, however, hispanic families are very close in ways American families are not, and I can understand how this can be hard for you to understand. Bear in mind, that while I was growing up, we often had family parties and then instead of going home like most people do after parties, they would just stay the night at my parents house. Not only did everyone say the night, we all shared the same rooms and cousins even shared the same bed. There was nothing unusual about this. I am married now, and my mother insists on coming over and staying the night when my husband is away on business trips. If that wasn't bad enough, she likes to sleep in the same bed with me. I don't mind really, I know it is just the way she and many other hispanc mothers are. I hope this helps.
Laci