I'm sorry you are suffering right now.
The Peaceful Pill e Handbook discusses many different ways to CBT. It also covers overdoses (of all kinds). You can find a link to download a pirated copy here in the forums.
Not all TCAs are the same. The ones prescribed today are rarely fatal, just make you really sick.
Same with benzoes. The needed amount to CBT is hard to keep down without your body violently trying to get rid of it.
If you must, take a "break" and take a few to sleep for 24 hrs. But it's a waste of good benzoes to try and overdose on them.
Been there. Done that.
Wasn't fun. Didn't change much.
Here is a thread you might find helpful:
'Don't try overdosing, unless....'
https://sanctioned-suicide.net/threads/dont-try-overdosing-unless.77167/