Why do we continue?

I ask myself everyday, why people fight to stay alive? I can’t wait for this life to be over. My sister is a 40, I am 41, she has cancer, and given 6 months to live. I am so jealous of her, she is the luckiest person I know.The only reason I stick around this hellish life, is to take care of my kids. They do not have anyone else in the world that would take care of them. I was married to their POS dad for 18 years, and he split, quite his job to get out of paying any child support. The job that he had only had for the last year we were together, its not like he ever paid for anything anyway. 6 years later I married again, he is 12 years younger, said he loved me, and my kids, and wanted to “take care of us”. I helped, and paid for everything for him to become a lic. building contractor, and he has since has two decent big jobs, and has walked off both of them. One was, he was remolding my bosses house, and my boss says he never wants to see his face again around my work. I have had this job for 10 years, its my only means of providing for my kids. I spent my entire savings on a terrible house because he wanted to work on it, and “make it beautiful” for us. Needless to say he never finished it. I have huge holes in the walls, we have 4000 sf, and 3 1/2 baths, only one bath works, and you can only get to 3 out of the 5 bedrooms. I gave my car to my oldest daughter, to go to college, depending on him to drive the kids and I where we need to go. That’s like a prison, I can’t afford to buy a car because of this house. My God I have terrible judgement. When ever I go anywhere, I am just amazed that women without a job, really ugly, or very fat, don’t take care of themselves, can find someone to love them enough to even go to work and contribute to the family. Yet I have NEVER ever had that. I am perfectly capable of working, and making a decent living. I have never expected anyone to support me, God forbid. How wonderful it would be to just have one person in this world that gave a shit enough about me to help, and if anything ever happens I could depend on. That’s all I have ever wanted in this life. Just to know I am loved for free, with no conditions. I have tried to live my life without ever hurting anyone, try to be a good person.  I have never cheated on my spouse, even though I am not attracted to him, I would never hurt another human being like that.I thought I believed in karma. Just like love, marriage, family, house, cars, etc. those are just bull shit things people tell us to set us up for constant disappointment. I don’t believe in love anymore, and that’s all I have ever lived for. Even if I find someone else, it might be good for a while, as soon as I let my guard down, and try to make it work, its always the same total disappointment. I can’t do it anymore. People always say you need to just love your kids, and that should be enough. I do love them with all of my heart and soul, they deserve so much better. I try so hard to be happy for them. I am so tired, I am one person, and its so hard to give, and give, and give, you get to a point that its all used up, I don’t have anything else to give.  I have two starting high school, as soon as they get to college, I can’t see any reason to continue. I just can’t bring myself to hurt them. But I want out sooo bad. Your life is shit when you start looking on line for the best way to end it. I am a planner, and when the time comes, I will have a perfect plan.