God...I'm not sure my choices are right...

My choices in life, are what I believe, the best to my ability.
I married this man, because I wanted a father for my child, not a child who thought that only having one set of grandparents was normal. I wanted someone to care at least half as much about me, as they did the child that they helped to create.
I feel like such a failure because I made the choice to get married, ignoring, once again, all the red flags and warning signs that I saw at the outset. Why do I put so much into something that I know will never come back to me?
Why do I care so much?
Why do I want someone to depend on? I know darned well, that the only person that I can depend on is myself.