JustSue I know what you are going through But please don't do anything that drastic. Your kids need you more then you my think right now. Your mother died when you were quite young as I understand. Think about what it did to you and then think about what it would do to your children.
I have been at the point where you are right now and it was the thought of what would happen to my children as a result that kept me going.
My Doctor put me on anti depressants which has helped a lot. If you are not taking any you should get to your Doctor asap. If you are taking some get to your Doctor asap and have them changed as it is obvious they are no longer working.
My love and prayers go out to you. If you need a surrogate mother I am offering my services as you are probably the same age as my children right now.
Tons of Hugs from Grannygray