I don't think my mother can handle me going to Uni

So, I'm 18, 19 in a month, and I was planning on going to Uni next year. I've already put it off for a year, instead opting to do one more year of college so that my mother could keep getting child benefits for me for one more year at least.
My mother is currently...a little bit unstable, to put it delicately. Not in the sense that she's erratic, but emotionally. A few months ago her mother died, and she broke up with her boyfriend around the same time and ever since she's been depressed, and much more clingy to me. She and I have always been close, but I think lately I've kind of ended up becoming her support system- though my older sisters still live with us, they're not really the affectionate kind.
I always knew it that it would be hard for her if I went, but especially with the death of her mother I think she's become much more aware of her own mortality and doesn't know what to do with her life from here on out and I think she sees taking care of me and being my mother, as her purpose right now. I also think she might think of me going as the end of her role as my parent, and the end of the "family" phase of her life.
I thought that it was going okay- she seemed neutral at the idea of me going to Uni, though also not overtly in support, and even brought me to an open day. Keeping in mind everything, I've picked universities under 1.5h away from my town, despite there not being many offering the course I want.
Last night she came home, came in my room and hugged me, saying she really needed a hug. She said something about how she missed her ex, and that she didn't know how to get over it. She asked me to come sit with her on the couch and hug her for a while. She then told me, for the first time in words, that she wasn't ready for me to leave. She said that for my sisters, she was ready for the day they'd go, they're adults at this point, but she didn't know if she could handle me going. Then she joked that she would come rent a room wherever I go- a joke she's made often in the past.

I dont know what to do. To me, my mother is the most important person in the world, and the strongest too. All my memories of her when I was growing up are of her being strong and decisive and dedicated- even when my piece of **** dad ****ed off she picked herself right up and took me to school on the back of her bike every day while working 3 jobs. Now that she's finally breaking, I'm scared about if she's going to be able to pick herself back up anymore.
I want to be successful enough so that I can finally put her out of work and buy her a house so that she never has to worry about losing a home again and I think going to university is the first step to that. I'm scared of leaving, but I also don't want to wait for my life to just happen for me anymore. But at the same time, I'm scared of leaving my mother alone. She's not ready to move into the next phase of her life, and I'm ready to move into mine.
My college is sending off our Uni applications today and I'm feeling genuinely trapped and I just want time to stop. I'm not even sure what advice I'm asking for here, I don't even think I know what my options might be, but so far all I've gotten from my brain and other people is a black and white "go" or "don't go", but none of it feels that simple.
What should I do?