<human>: She constantly frustrates me in I one way or another with her moods but this just drew the line. 

I told her earlier that I *might* meet up with a guy later. Later on she's like 
'so when are you leaving?'
I might not, thinking to work on homework and sleep.
'REALLY?' (Annoyed tone) 
umm, I never said I was going for sure just that it *might* be an option. 
'I know' 
then why are you pissed off?
'I'm not' 
well you sure sound like it 
'I have a right to my feelings don't I?' 
Yeah, but don't take it out on me. 
'I was just hoping to have the house to myself' 

I get to my room only to find this message in my facebook:

look i just have been upset and depressed since I left today, I needed the house to myself and you leaving sounded kinda nice. Yeah i'm disappointed and a little upset, but why would you be upset if I am? Why shouldn't I have the right to my own feelings if I can manage them so they don't affect you?
Have a lovely evening and sleep well.

What do I say to make her understand how that made me feel?

Could you distill the essence of the text into 1-3 sentences?
<bot>: roommate thinks that its okay to express how she feels even if its being mad at me for something I didn't say I'd do for certain.