Me [20M] with my father [40M] who I met months ago, and his girlfriend [26/7F]. I feel like I'm in a mess.

So this is gonna be weird all around because that's how my life goes, apparently.
I have a job, a girlfriend and am quite happy. We live together, we have our own little business and everything. I never knew my real parents. And forthe logest time, that didn't bother me. Then I met my uncle, by chance and soon after I met my father. They're twins, my uncle and my father, and my father, well, he didn't know about me. At all. He had a one nght stand, I was the result but he was long gone before he could know about me.
Anyway I won't bother anyone with details that mean nothing to th story. We're getting along, my father and I. He's rather reserved and very introverted, my uncle is the opposite. It's been nice, finding them, I mean.
Now, to the weird part. There's this girl, she's around 26/27. Very gorgeous, very smart, funny and somehow very reserved too. She's, apparently, my father's girlfriend. Their story is pretty deep from what my uncle tells me. Like, she understands my father and vice versa. She's been through a lot, appafrently, a lot more than she should.
Thing is, she started getting close to me too. And I thought I was going to hate it. But I actually like having her around. She knows my father and I are very awkward around each other still, but she keeps coming up with these plans to get us to talk more. And they're very obvious and we're always on to her but the thing is, it works. I've been getting closer to my dad thanks to her. And in the process, I don't know, I guess I started seeing her in a motherly figure. And it hit me how weird this is. She's closer to my age. She could be my sister. Instead I look at her as a mother.
And that was the problem until I find out she's pregnant with my father's child and it's high risk and she's been feeling ill so she's spending the night in observation.
I'm with my father. And I'm feeling so scared for her. And feeling weird about it. What should I do in this situation? Any advice would help becuse I honestly don't know how to act.

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tl.dr: found my dad, dad is cool, his girlfriend is cool and i'm feeling weird about all of this and the things that are happening.


Source.