Girlfriend F/32 upset I M/37 want to see my twin sister who has been admitted to a mental hospital is she being controlling?

My girlfriend is 4 months pregnant, throughout the relationship (1 year) she gets upset when I see my friends, resorting to either blocking me on social media or breaking up with me.

Her falling pregnant was an accident but we’ve decided to go ahead and have the baby, we’re both very excited.

I work week on week off and my week off I’ll make sure I take her out to lunch or dinner at least once, I spend 90% of my time with her. I only want to catch up with my mates for maybe a quick beer once or twice a week usually to watch a football game and that’s it. When I try and leave the house she either gets angry at me for going or starts crying and says I’m prioritising my friends over her.

I’ve sat down with her and explained that she is the most important person in my life but I’m still allowed to see my friends.

Recently my mum called me and said my twin sister had to check herself into a mental hospital and the only person she wants to see is me because of how close we are. My girlfriend and I have been fighting and during a fight she brought up how my real father left because he knew I was a sociopath, this was after me going to see my friends for a drink, after being accused of other things by her I shut down and said we’ll talk in the morning please, she ended up packing up and leaving at 3am then proceeded to block me and not tell me where she is.

I finally was able to get in contact with her and suggested therapy together which she agreed to then I had to tell her I have to fly 6 hours across the country to see my twin sister

She is now telling me I don’t care about her that I care more for my sister than her. That she needs help because she feels she’s going to end up in a hospital. I explained I can be there for her and my sister and even suggested she can come with me. This was met with I’d rather fly to see my sister than her.

What is going on?