Have you heard about therapy?
I strongly suggest you call a hospital or go to your doctor and tell them what has happened. Therapy is excellent. Ask the doctor to recommend a therapist.
The reality is you are very strong and very confident. It takes a lot of confidence to believe you are right that life isn't worth living. It takes a lot of strength to prepare and drink drain cleaner. It sounds like you were very hard on yourself. You are very hard on yourself, drinking poison over a failed relationship and mistakes is being very hard on yourself. I'm glad you didn't kill yourself, once you learn how to direct your strength, confidence, and determination towards your own desires you will be a great person.
Talk to a doctor and start seeing a therapist.