Blueberry, congrats! One of my close friends' son just started at U Mass Med School, after working for a few years. He is loving it.
Yes, it will be hard, but, you will still have time for some fun, if you plan well. During the short (and aborted) stint I did in a PhD program, I learned very quickly that it was really important to continue socializing and having fun with people from my former life.
Withm, hope you are healing well.