Sometimes asking for help during the darkest times is very hard so if you feel you can't speak to someone try writing to them.
When i was feeling very depressed and suicidal i didn't feel i could talk to my doctor so i wrote him a letter and booked an appointment and handed him a letter.
Tell your doctor how your feeling, how long it's been going on for and if you know what may have triggered the thoughts. Feeling Suicidal doesn't make you MAD or mental! It just means you need a little bit of help and in life we all need help at sometime or other.
Keeping a diary can help, i used to mark my day out of 10 (10 being the best) and and put a little comment about anything that may have triggered my score.
Remember Suicide is a permanent solution to a temporary problem.
Helpful link http://www.metanoia.org/suicide/