<human>: Could you distill the essence of the text into 1-3 sentences?

So as it says, my girlfriend allowed her male friend to stay over at hers 
for a week while he is visiting the city. The problem is that she lives in a tiny one room apartment, so he is staying literally in her room sharing a bed with her.
At no point was I asked if I am ok with that. I didn't want to cause drama or ruin her friend's vacation, since I was just informed of that decision after the fact. However after thinking about it I feel like that is something I cannot tolerate.
There are really no reasons to suspect her of anything, it's the fact that she would put me in situation like this that really puzzles me. Why  does she think it's ok? I think I am open-minded enough and I would have no problems with people sharing a bed if there is a need, however in this case I believe there were more appropriate options.
I think it was inconsiderate enough of her to the point that I am going to tell her that it is not something I want to deal with ever again and request an std test after he leaves. Again, I don't really suspect anything but I don't want to take any chances and if my feelings were not considered, why should I be nice about her's.
Am I overreacting?
<bot>: My girlfriends male friend stays at hers, sharing a bed. I am not ok with that, don't know how to express my concerns.