Families stick together and are there for each other. Your family can give you some support, but you are right, they cannot bear this burden for you. The good thing is you don't have to try to handle it all by yourself. Your wife can give you some support. Your doctor or therapist is there to help you and to teach you to help yourself.

And I don't think you are right when you say "they did not sign up for this." Being a family means there's no such thing. You are there for each other through the hardest things. The same way you would be there for them if the shoe was on the other foot. It is okay to say to your wife, I need your help. Saying that to my wife was the hardest thing, but I am glad I did. She helps me. Of course, there is a limit to what I can ask from her, when I should get outside help, but that's not the same thing as trying to insulate your family from your internal pain.
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1. Be impeccable with your word.
2. Donít take anything personally.
3. Donít make assumptions.
4. Always do your best.

― Miguel Ruiz, The Four Agreements