You going off to college is very healthy for both of you. It sounds like you have to be the adult in the room when you're with your mother. Her issues definitely sound a lot more serious than empty next syndrome. It's good you realize that.

Dealing with her neediness will probably be an on-going struggle for you. She does need to be treated with kindness, but should not be allowed to manipulate you. It sounds like you have a good handle of the situation.

Enjoy going off to school. Invest in new relationships there. There will be understanding people whom you will meet. You will find new sources of support for yourself . . . and it will be a healthier form of support.