Dealing with negative emotions

I’ve been dealing with some negative emotions that keep coming back for the past few days.
I can’t find the exact reason, my brain is just on super negative mode.
I try to feel and process my emotions, but I don’t know how to control how I act with other people and that freaks me out.

I get completely sensitive and completely cut myself out from other people. I feel disconnected with my girlfriend because a lot of what she says triggers me, and I know right now I am acting defensive and snappy. And then the result is that I feel more and more alone, more and more disconnected, and that’s what really scares me. Which make me go into thinking “ok get out of this mood fast or else you’re gonna become all alone and everyone is gonna hate you!” which just obviously makes it worst.

I don’t know how to process my negative emotions without “acting on them” when I’m with other people.

And that’s what really scares me.

It’s hard to just feel and process it when you are with other people.

Any help on that?