Where do you live? There are a lot of short-term programs that basically function as blindness boot camp. Many people are blinded in accidents etc. and need training on short notice. You may be able to do it over the summer and still go to grad school on schedule (congrats on the degree!) but it really depends on how quickly your vision goes, how quickly you pick up the skills, and how hard you are willing to work. Though I'm sure it's traumatic to be losing vision, don't forget there are lots of people with low to no vision who are out there doing great things. Definitely follow up with counseling as well; it's no small thing to lose the use of a sense.

I'd highly recommend an organization like the NFB, because I think it would help your self esteem and motivation a lot to meet some successful blind people and see how well they adapt.

You will have to learn to do many things differently, but thanks to technology you can still have a great career.

Organizations like the NFB are great but definitely keep in mind that there is more than one way to do things. There's a lot to learn out there and don't let anybody tell you but you can't do something. If you find a way that works for you then roll with it. There's lots of help out there. I lost my site when I was 22 years old and I can tell you that's it's really not as bad as you imagine it will be. Just have confidence and be willing to work hard and never except defeat. Making the mental decision to succeed will set you up for success

If you're in UK, call RNIB - they have a lot of resources to get started.
In US, NFB was already mentioned... But there are other orgs too, so a lot depends on the city and state you're in.
In Canada they have CNIB, Australia has Vision Australia.
For other countries... Where are you?

It's ok to be frustrated. You'll might have to learn to do a lot of things in new ways.
But that doesn't have to stop you from being happy and having a satisfactory life. One skill at a time...
A blind coucelor would probsbly be useful too.