I just joined this forum today and your post was the first one I noticed.
I'm so sorry you are feeling that you can't take it anymore. I'm not sure if you are feeling suicidal, but if you are, please call the National Suicide Prevention Lifeline at 800-273-8255 or go to your nearest emergency room.
Please know that you are not alone. I am also in my 40's and have had a debilitating chronic pain disorder since age 31. I too, have a mental illness as well. Physical & emotional pain certainly do take their toll on the psyche. It's good that you're venting on here instead of keeping your frustrations inside where they only serve to cause even more pain.
Do you have a psychologist and a pain management doc/clinic? What do you do for emotional self-care (hobbies, etc.)?
I hope you're having a better day today. Please keep us updated.