He sounds like a total jerk.
I have been known to confront people "Julia Sugarbaker style" (you know, from Designing Women...) when they are messing around on my friends, etc.
I would probably just bring it up with this "non-boyfriend" guy. If you catch him doing or saying something inappropriate, just say "Excuse me, but does my roommate know that you enjoy giving massages and butt-grabs as casually as a handshake? 'Cause if you forgot to tell her about those habits, I am sure I can manage to remember to say something about it!"
If you don't want to talk to him, you could always just casually have your hit-on friends over one day and bring it up nonchalantly in conversation with your roomie so that you have back-up...this also makes it harder for her to blame you for saying such terrible things about her baby
Anyway, that situation sucks. Good luck.
