Yes you should most definitely tell her. If you don't have a new therapist lined up you should enlist the help of your old therapist to help you get one.
Another thing, get copies of all your medical records before you leave carry them with you so, Lord forbid you would have a psychotic break while you are in transit to your new place. If you are on any medications make sure you have the prescription print out you get when you get one filled and take them with you.
If she is a good person as most Social Workers are she will be sympathetic to your concerns and will try to help any way she can. Having suicidal thoughts is one thing, going as far as to plan how you would do it is another. I implore you that if you have a plan in mind already PLEASE post pone your trip and seek help before you go. Suicidal thoughts are not normal, there is something weighing heavy on your mind to bring on this type of thought process. If the feelings get so strong you feel you just can't resist please call this number 1-800-273-8255, Established by the" Wounded Warrior Program" they are there to help anyone contemplating suicide.
Anxiety can bring on so many different feelings, they have meds to calm those feelings. I'm not saying medication is the answer, Biofeedback or Meditation is amazing if practiced in the right manner and on a daily basis several times a day if need be. I'm just guessing but I bet your whole life you have been a go getter going at every job, assignment or what ever in HI-GEAR. You could even be a little OCD or ADHD those are not bad things if you learn how to harness that energy and focus it on creative things.
Graduation, WOW this is a milestone in your life try to embrace it and take your life to the next level. I know one thing for sure you are an intelligent person, I would bet, Beautiful, with a big heart. Why, because it takes that type of person to realize there is a problem and seeking out help for it.
Good luck on your new adventure and I will leave you with 2 things that have helped me down this path we call life.
1. Take it one day at time, we are never promised tomorrow so why worry about it.
2. Last but most certainly not least a little prayer that gave me a new perspective on life and it goes like this.
God grant me the Serenity to accept the things I can not change, Courage to change the things I can and the Wisdom to know the difference.
May God Bless and Keep you.
I do not write anything that I have not experienced, So the answer to question number one is. "The School of Hard Knocks".