I'm afraid that I'm on the verge of what I believe is a complete mental collapse.
Oh no, I'm sorry to hear that. Why do you feel you're at the end of your rope?
I'm avoiding my own thoughts because I'm scared of them and I can't even concentrate.
Avoiding your thoughts will run you ragged and put you at your wit's end. Everyone has a limit and if you find yours you might not be able to recover. Get some help from a therapist and learn some techniques for controlling your thoughts.
I don't think a therapist could help me.
I'm sure that a therapist would be able to help you control your thoughts and feel better. They're trained to help people get through difficult situations like the one you're in.