It is good that you are sharing your feelings and reaching out for help. Drinking to solve your problems only makes you less able to control your emotions. It's very dangerous to drink when you are having suicidal thoughts. Talk to someone who can help you. Try your school counselor or another adult that you can trust. If you need more immediate help to keep yourself safe, call 911 or get to the Emergency Room of your local hospital.
It doesn't sound like the people you thought were your friends, really were. If they were, they would not have deserted you in your time of need.
Do you have a job or hobbies? If you do, spend more time with them to keep you from being alone and resorting to alcohol to make you feel better.
Since you are a Senior, try setting some goals for yourself. Short term goals- like daily or weekly ones, then look at what you want to be doing 6 months from now and figure out what it will take to get there.
Sometimes it is easy to get caught up things that happened in the past and not focus forward on how you would like things to be in the future.
Take control and move forward!
Pat-Counselor