How can it hurt you? I mean as long its not for a long time it cant really hurt you. One night or a few days cant be that bad.
And yeah i get that. But you could try not telling your therapist that you are suicidal. Just tell her about all your problems in detail, every single one just like in your first post. but leave out the part about being suicidal. Say you are really depressed but not suicidal. Then the therapist will help you with your problems but your mom will never find out that you're suicidal.
Then if you still need help with the suicidal part call a teen suicide hotline. They will give you advice and help you over the phone but keep your call anonymous so no one will find out. I am posting a link below for such hotlines.
Here is one of the better ones for you from the link:
YOUTH CRISIS HOTLINE
1(800)448-4663
Anonymous. Available 24 hours a day. No problem is too big or too small.
LINK:
Teen Section
the first part of the link is about the dangers of meth, but scroll down about halfway and there are help hotlines for a variety of problems