Well, she is at least out of the hospital
And, I know the feeling. My parents decided to separate when I was in 6th grade. I had a hard time at first, seeing my dad with someone else. Especially when she lived in Canada and I never really saw them together or I saw her once or twice a year. It was weird.
But over time, you get used to it. My dad is incredibly happy with my Canadian mom to be and I'm getting to be more ok with it. Still have my issues but who doesn't.
I think thinking ahead is a good thing. You can foresee possible problems but also see amazing things. I'm happy for your dad!
Being single doesn't make you weak, it means that you are strong enough to be on your own; Being alone could be a good thing, because there is no drama involved in your life, no pain, and free to do what ever you want. Life is too short to be chasing those who aren't even worth fighting for, you are worth more than that.