Oh my goodness! I am so sorry that I am just now reading and responding to your post!
I am so angry with your oncologist right now! He/she has no way of predicting the future. For he/she to tell you that you only have 1 to 5 years to live is just plain wrong.
Having stage 4 inflammatory breast cancer with severe bones mets myelf, I have read several other articles that would imply the same thing that your onc said. The problem being that those articles are OLD and OUTDATED. Not only that, the majority of case studies done are done on women twice our age (I'm assuming you are under 40 given you have children under the age of 18). Of course someone who is 80 is going to fair way worse than someone who is 40.
I have to tell you that when I was first diagnosed I belived everything I read and was terrified that I would be dead in 5 years. One day at an onc appointment my husband expressed my concern to my onc. My onc smiled and told me to get that crazy idea out of my head. He expects me to live 20+ years.
I am so angry right now. I'm glad that you are going for a second opinion. While there I would start looking for another onc. You want someone who is going to fight to keep you alive, not give you an expiration date.
It sounds as if we are in a similar health/family situation (I have three children ages 13, 15, and 21). Please if you need someone to vent to feel free to email me at firstname.lastname@example.org .