Suicidal ideation is very scary. It's time to talk to some one who can actively help you. Call your T or a hotline. Talk to some one at school or mother if your more comfortable with her. Maybe for your next visit to your T, you could write it down in a letter so you don't have to say it... you just hand her the letter.

Don't let your silence keep you prisoner. It isn't easy or simple to be brave and speak out... but it is better than hurting yourself. Depression is very isolating. Please, seek help before it becomes too dangerous for you. Being this desperate is a horrible feeling, especially when it doesn't have to be this way. You aren't alone.