Okay, I need help or advice or your opinions on this, please!!!(please no questions on why I snooped or why am I looking, and/or why or not I trust him if I do look)

How would you feel if your boyfriend talked about working with another friend (who is a girl) if he changed his major in college for it?

Also how would you feel if he invited that girl over to his home (alone with her or not) and said he better not because his gf might "flipshit"

Yes, I went through his texts. Nobody needs to know why, (rather it was curiosity or jealousy or no trust or anything) I just need opinions and advice.

Yes, this girl knows who I am, and they've talked about me and things. (Like how I am)

No, she's never met me. But she's hung out with him twice in our relationship of 10 months WITHOUT me knowing.

What would you do or how would you feel about this? I'm so loss..and just last week he got mad and said maybe we shouldn't try anymore because an old friend asked to go to the mall with him and his cousins (I told him no) I told him what he asked because I am open to other people and who I hangout with, apparently he's not.